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# Möbius function

Möbius function
You are encouraged to solve this task according to the task description, using any language you may know.

The classical Möbius function: μ(n) is an important multiplicative function in number theory and combinatorics.

There are several ways to implement a Möbius function.

A fairly straightforward method is to find the prime factors of a positive integer n, then define μ(n) based on the sum of the primitive factors. It has the values {−1, 0, 1} depending on the factorization of n:

• μ(1) is defined to be 1.
• μ(n) = 1 if n is a square-free positive integer with an even number of prime factors.
• μ(n) = −1 if n is a square-free positive integer with an odd number of prime factors.
• μ(n) = 0 if n has a squared prime factor.

• Write a routine (function, procedure, whatever) μ(n) to find the Möbius number for a positive integer n.
• Use that routine to find and display here, on this page, at least the first 99 terms in a grid layout. (Not just one long line or column of numbers.)

## ALGOL 68

Translation of: C
`BEGIN    # show the first 199 values of the moebius function                 #    INT sq root = 1 000;    INT mu max  = sq root * sq root;    [ 1 : mu max ]INT mu;    FOR i FROM LWB mu TO UPB mu DO mu[ i ] := 1 OD;    FOR i FROM 2 TO sq root DO        IF mu[ i ] = 1 THEN            # for each factor found, swap + and -                       #            FOR j FROM i     BY i     TO UPB mu DO mu[ j ] *:= -i OD;            FOR j FROM i * i BY i * i TO UPB mu DO mu[ j ]  :=  0 OD        FI    OD;    FOR i FROM 2 TO UPB mu DO        IF   mu[ i ] =  i THEN mu[ i ] :=  1        ELIF mu[ i ] = -i THEN mu[ i ] := -1        ELIF mu[ i ] <  0 THEN mu[ i ] :=  1        ELIF mu[ i ] >  0 THEN mu[ i ] := -1      # ELSE mu[ i ] =  0 so no change #        FI    OD;    print( ( "First 199 terms of the möbius function are as follows:", newline, "    " ) );    FOR i TO 199 DO        print( ( whole( mu[ i ], -4 ) ) );        IF ( i + 1 ) MOD 20 = 0 THEN print( ( newline ) ) FI    ODEND`
Output:
```First 199 terms of the möbius function are as follows:
1  -1  -1   0  -1   1  -1   0   0   1  -1   0  -1   1   1   0  -1   0  -1
0   1   1  -1   0   0   1   0   0  -1  -1  -1   0   1   1   1   0  -1   1   1
0  -1  -1  -1   0   0   1  -1   0   0   0   1   0  -1   0   1   0   1   1  -1
0  -1   1   0   0   1  -1  -1   0   1  -1  -1   0  -1   1   0   0   1  -1  -1
0   0   1  -1   0   1   1   1   0  -1   0   1   0   1   1   1   0  -1   0   0
0  -1  -1  -1   0  -1   1  -1   0  -1  -1   1   0  -1  -1   1   0   0   1   1
0   0   1   1   0   0   0  -1   0   1  -1  -1   0   1   1   0   0  -1  -1  -1
0   1   1   1   0   1   1   0   0  -1   0  -1   0   0  -1   1   0  -1   1   1
0   1   0  -1   0  -1   1  -1   0   0  -1   0   0  -1  -1   0   0   1   1  -1
0  -1  -1   1   0   1  -1   1   0   0  -1  -1   0  -1   1  -1   0  -1   0  -1
```

## Arturo

`mobius: function [n][    if n=0 -> return ""    if n=1 -> return 1    f: factors.prime n     if f <> unique f -> return 0    if? odd? size f -> return neg 1    else -> return 1] loop split.every:20 map 0..199 => mobius 'a ->    print map a => [pad to :string & 3]`
Output:
```      1  -1  -1   0  -1   1  -1   0   0   1  -1   0  -1   1   1   0  -1   0  -1
0   1   1  -1   0   0   1   0   0  -1  -1  -1   0   1   1   1   0  -1   1   1
0  -1  -1  -1   0   0   1  -1   0   0   0   1   0  -1   0   1   0   1   1  -1
0  -1   1   0   0   1  -1  -1   0   1  -1  -1   0  -1   1   0   0   1  -1  -1
0   0   1  -1   0   1   1   1   0  -1   0   1   0   1   1   1   0  -1   0   0
0  -1  -1  -1   0  -1   1  -1   0  -1  -1   1   0  -1  -1   1   0   0   1   1
0   0   1   1   0   0   0  -1   0   1  -1  -1   0   1   1   0   0  -1  -1  -1
0   1   1   1   0   1   1   0   0  -1   0  -1   0   0  -1   1   0  -1   1   1
0   1   0  -1   0  -1   1  -1   0   0  -1   0   0  -1  -1   0   0   1   1  -1
0  -1  -1   1   0   1  -1   1   0   0  -1  -1   0  -1   1  -1   0  -1   0  -1```

## AWK

` # syntax: GAWK -f MOBIUS_FUNCTION.AWK# converted from JavaBEGIN {    printf("first 199 terms of the mobius sequence:\n   ")    for (n=1; n<200; n++) {      printf("%3d",mobius(n))      if ((n+1) % 20 == 0) {        printf("\n")      }    }    exit(0)}function mobius(n,  i,j,mu_max) {    if (n in MU) {      return(MU[n])    }    mu_max = 1000000    for (i=0; i<mu_max; i++) { # populate array      MU[i] = 1    }    for (i=2; i<=int(sqrt(mu_max)); i++ ) {      if (MU[i] == 1) {        for (j=i; j<=mu_max; j+=i) { # for each factor found, swap + and -          MU[j] *= -i        }        for (j=i*i; j<=mu_max; j+=i*i) { # square factor = 0          MU[j] = 0        }      }    }    for (i=2; i<=mu_max; i++) {      if (MU[i] == i) {        MU[i] = 1      }      else if (MU[i] == -i) {        MU[i] = -1      }      else if (MU[i] < 0) {        MU[i] = 1      }      else if (MU[i] > 0) {        MU[i] = -1      }    }    return(MU[n])} `
Output:
```first 199 terms of the mobius sequence:
1 -1 -1  0 -1  1 -1  0  0  1 -1  0 -1  1  1  0 -1  0 -1
0  1  1 -1  0  0  1  0  0 -1 -1 -1  0  1  1  1  0 -1  1  1
0 -1 -1 -1  0  0  1 -1  0  0  0  1  0 -1  0  1  0  1  1 -1
0 -1  1  0  0  1 -1 -1  0  1 -1 -1  0 -1  1  0  0  1 -1 -1
0  0  1 -1  0  1  1  1  0 -1  0  1  0  1  1  1  0 -1  0  0
0 -1 -1 -1  0 -1  1 -1  0 -1 -1  1  0 -1 -1  1  0  0  1  1
0  0  1  1  0  0  0 -1  0  1 -1 -1  0  1  1  0  0 -1 -1 -1
0  1  1  1  0  1  1  0  0 -1  0 -1  0  0 -1  1  0 -1  1  1
0  1  0 -1  0 -1  1 -1  0  0 -1  0  0 -1 -1  0  0  1  1 -1
0 -1 -1  1  0  1 -1  1  0  0 -1 -1  0 -1  1 -1  0 -1  0 -1
```

## BASIC256

Translation of: FreeBASIC
`function mobius(n)	if n = 1 then return 1	for d = 2 to int(sqr(n))		if n mod d = 0 then			if n mod (d*d) = 0 then return 0			return -mobius(n/d)		end if	next d	return -1end function outstr\$ = " .   "for i = 1 to 200	if mobius(i) >= 0 then outstr\$ += " "	outstr\$ += string(mobius(i)) + "   "	if i mod 10 = 9 then		print outstr\$		outstr\$ = ""	end ifnext iend`
Output:
```Igual que la entrada de FreeBASIC.
```

## C

Translation of: Java
`#include <math.h>#include <stdio.h>#include <stdlib.h>#include <string.h> int main() {    const int MU_MAX = 1000000;    int i, j;    int *mu;    int sqroot;     sqroot = (int)sqrt(MU_MAX);     mu = malloc((MU_MAX + 1) * sizeof(int));     for (i = 0; i < MU_MAX;i++) {        mu[i] = 1;    }     for (i = 2; i <= sqroot; i++) {        if (mu[i] == 1) {            // for each factor found, swap + and -            for (j = i; j <= MU_MAX; j += i) {                mu[j] *= -i;            }            // square factor = 0            for (j = i * i; j <= MU_MAX; j += i * i) {                mu[j] = 0;            }        }    }     for (i = 2; i <= MU_MAX; i++) {        if (mu[i] == i) {            mu[i] = 1;        } else if (mu[i] == -i) {            mu[i] = -1;        } else if (mu[i] < 0) {            mu[i] = 1;        } else if (mu[i] > 0) {            mu[i] = -1;        }    }     printf("First 199 terms of the möbius function are as follows:\n    ");    for (i = 1; i < 200; i++) {        printf("%2d  ", mu[i]);        if ((i + 1) % 20 == 0) {            printf("\n");        }    }     free(mu);    return 0;}`
Output:
```First 199 terms of the m÷bius function are as follows:
1  -1  -1   0  -1   1  -1   0   0   1  -1   0  -1   1   1   0  -1   0  -1
0   1   1  -1   0   0   1   0   0  -1  -1  -1   0   1   1   1   0  -1   1   1
0  -1  -1  -1   0   0   1  -1   0   0   0   1   0  -1   0   1   0   1   1  -1
0  -1   1   0   0   1  -1  -1   0   1  -1  -1   0  -1   1   0   0   1  -1  -1
0   0   1  -1   0   1   1   1   0  -1   0   1   0   1   1   1   0  -1   0   0
0  -1  -1  -1   0  -1   1  -1   0  -1  -1   1   0  -1  -1   1   0   0   1   1
0   0   1   1   0   0   0  -1   0   1  -1  -1   0   1   1   0   0  -1  -1  -1
0   1   1   1   0   1   1   0   0  -1   0  -1   0   0  -1   1   0  -1   1   1
0   1   0  -1   0  -1   1  -1   0   0  -1   0   0  -1  -1   0   0   1   1  -1
0  -1  -1   1   0   1  -1   1   0   0  -1  -1   0  -1   1  -1   0  -1   0  -1```

## C++

Translation of: Java
`#include <iomanip>#include <iostream>#include <vector> constexpr int MU_MAX = 1'000'000;std::vector<int> MU; int mobiusFunction(int n) {    if (!MU.empty()) {        return MU[n];    }     // Populate array    MU.resize(MU_MAX + 1, 1);    int root = sqrt(MU_MAX);     for (int i = 2; i <= root; i++) {        if (MU[i] == 1) {            // for each factor found, swap + and -            for (int j = i; j <= MU_MAX; j += i) {                MU[j] *= -i;            }            // square factor = 0            for (int j = i * i; j <= MU_MAX; j += i * i) {                MU[j] = 0;            }        }    }     for (int i = 2; i <= MU_MAX; i++) {        if (MU[i] == i) {            MU[i] = 1;        } else if (MU[i] == -i) {            MU[i] = -1;        } else if (MU[i] < 0) {            MU[i] = 1;        } else if (MU[i] > 0) {            MU[i] = -1;        }    }     return MU[n];} int main() {    std::cout << "First 199 terms of the möbius function are as follows:\n    ";    for (int n = 1; n < 200; n++) {        std::cout << std::setw(2) << mobiusFunction(n) << "  ";        if ((n + 1) % 20 == 0) {            std::cout << '\n';        }    }     return 0;}`
Output:
```First 199 terms of the m÷bius function are as follows:
1  -1  -1   0  -1   1  -1   0   0   1  -1   0  -1   1   1   0  -1   0  -1
0   1   1  -1   0   0   1   0   0  -1  -1  -1   0   1   1   1   0  -1   1   1
0  -1  -1  -1   0   0   1  -1   0   0   0   1   0  -1   0   1   0   1   1  -1
0  -1   1   0   0   1  -1  -1   0   1  -1  -1   0  -1   1   0   0   1  -1  -1
0   0   1  -1   0   1   1   1   0  -1   0   1   0   1   1   1   0  -1   0   0
0  -1  -1  -1   0  -1   1  -1   0  -1  -1   1   0  -1  -1   1   0   0   1   1
0   0   1   1   0   0   0  -1   0   1  -1  -1   0   1   1   0   0  -1  -1  -1
0   1   1   1   0   1   1   0   0  -1   0  -1   0   0  -1   1   0  -1   1   1
0   1   0  -1   0  -1   1  -1   0   0  -1   0   0  -1  -1   0   0   1   1  -1
0  -1  -1   1   0   1  -1   1   0   0  -1  -1   0  -1   1  -1   0  -1   0  -1```

## D

Translation of: C++
`import std.math;import std.stdio; immutable MU_MAX = 1_000_000; int mobiusFunction(int n) {    static initialized = false;    static int[MU_MAX + 1] MU;     if (initialized) {        return MU[n];    }     // populate array    MU[] = 1;    int root = cast(int) sqrt(cast(real) MU_MAX);     for (int i = 2; i <= root; i++) {        if (MU[i] == 1) {            // for each factor found, swap + and -            for (int j = i; j <= MU_MAX; j += i) {                MU[j] *= -i;            }            // square factor = 0            for (int j = i * i; j <= MU_MAX; j += i * i) {                MU[j] = 0;            }        }    }     for (int i = 2; i <= MU_MAX; i++) {        if (MU[i] == i) {            MU[i] = 1;        } else if (MU[i] == -i) {            MU[i] = -1;        } else if (MU[i] < 0) {            MU[i] = 1;        } else if (MU[i] > 0) {            MU[i] = -1;        }    }     initialized = true;    return MU[n];} void main() {    writeln("First 199 terms of the möbius function are as follows:");    write("    ");    for (int n = 1; n < 200; n++) {        writef("%2d  ", mobiusFunction(n));        if ((n + 1) % 20 == 0) {            writeln;        }    }}`
Output:
```First 199 terms of the m├╢bius function are as follows:
1  -1  -1   0  -1   1  -1   0   0   1  -1   0  -1   1   1   0  -1   0  -1
0   1   1  -1   0   0   1   0   0  -1  -1  -1   0   1   1   1   0  -1   1   1
0  -1  -1  -1   0   0   1  -1   0   0   0   1   0  -1   0   1   0   1   1  -1
0  -1   1   0   0   1  -1  -1   0   1  -1  -1   0  -1   1   0   0   1  -1  -1
0   0   1  -1   0   1   1   1   0  -1   0   1   0   1   1   1   0  -1   0   0
0  -1  -1  -1   0  -1   1  -1   0  -1  -1   1   0  -1  -1   1   0   0   1   1
0   0   1   1   0   0   0  -1   0   1  -1  -1   0   1   1   0   0  -1  -1  -1
0   1   1   1   0   1   1   0   0  -1   0  -1   0   0  -1   1   0  -1   1   1
0   1   0  -1   0  -1   1  -1   0   0  -1   0   0  -1  -1   0   0   1   1  -1
0  -1  -1   1   0   1  -1   1   0   0  -1  -1   0  -1   1  -1   0  -1   0  -1```

## F#

This task uses Extensible Prime Generator (F#)

` // Möbius function. Nigel Galloway: January 31st., 2021let fN g=let n=primes32()         let rec fN i g e l=match (l/g,l%g,e) with (1,0,false)->i                                                  |(n,0,false)->fN (0-i) g true n                                                  |(_,0,true) ->0                                                  |_          ->fN i (Seq.head n) false l         fN -1 (Seq.head n) false glet mobius=seq{yield 1; yield! Seq.initInfinite((+)2>>fN)}mobius|>Seq.take 500|>Seq.chunkBySize 25|>Seq.iter(fun n->Array.iter(printf "%3d") n;printfn "") `
Output:
```  1 -1 -1  0 -1  1 -1  0  0  1 -1  0 -1  1  1  0 -1  0 -1  0  1  1 -1  0  0
1  0  0 -1 -1 -1  0  1  1  1  0 -1  1  1  0 -1 -1 -1  0  0  1 -1  0  0  0
1  0 -1  0  1  0  1  1 -1  0 -1  1  0  0  1 -1 -1  0  1 -1 -1  0 -1  1  0
0  1 -1 -1  0  0  1 -1  0  1  1  1  0 -1  0  1  0  1  1  1  0 -1  0  0  0
-1 -1 -1  0 -1  1 -1  0 -1 -1  1  0 -1 -1  1  0  0  1  1  0  0  1  1  0  0
0 -1  0  1 -1 -1  0  1  1  0  0 -1 -1 -1  0  1  1  1  0  1  1  0  0 -1  0
-1  0  0 -1  1  0 -1  1  1  0  1  0 -1  0 -1  1 -1  0  0 -1  0  0 -1 -1  0
0  1  1 -1  0 -1 -1  1  0  1 -1  1  0  0 -1 -1  0 -1  1 -1  0 -1  0 -1  0
1  1  1  0  1  1  0  0  1  1 -1  0  1  1  1  0  1  1  1  0  1 -1 -1  0  0
1 -1  0 -1 -1 -1  0 -1  0  1  0  1 -1 -1  0 -1  0  0  0  0 -1  1  0  1  0
-1  0  1  1 -1  0 -1 -1  1  0  0  1 -1  0  1 -1  1  0 -1  0 -1  0 -1  1  0
0 -1  1  0  0 -1 -1 -1  0 -1 -1  1  0  0 -1  1  0 -1  0  1  0  0  1  1  0
1  1  1  0  1  0 -1  0  1 -1 -1  0 -1  1  0  0 -1 -1  1  0  1 -1  1  0  0
1  1  0  1  1 -1  0  0  1  1  0 -1  0  1  0  1  0  0  0 -1  1 -1  0 -1  0
0  0 -1 -1  1  0 -1  1 -1  0  0  1  0  0  1 -1 -1  0  0 -1  1  0 -1 -1  0
0  1  0 -1  0  1  1 -1  0 -1  1  0  0 -1  1  1  0  1  1  1  0 -1  1 -1  0
-1 -1  1  0  0 -1  1  0 -1 -1  1  0  1  0  1  0  1 -1 -1  0 -1  1  0  0  0
-1  1  0 -1 -1 -1  0 -1 -1 -1  0  1 -1 -1  0  0 -1 -1  0  1  1  1  0 -1  0
1  0  1  1 -1  0 -1  1  0  0 -1  1 -1  0 -1  1 -1  0  1 -1  1  0  1 -1  0
0  0  1 -1  0  1  1 -1  0  1  0 -1  0  1  0 -1  0  1 -1  0  0  1 -1 -1  0
```

## Factor

The `mobius` word exists in the `math.extras` vocabulary. See the implementation here.

Works with: Factor version 0.99 2020-01-23
`USING: formatting grouping io math.extras math.ranges sequences ; "First 199 terms of the Möbius sequence:" print199 [1,b] [ mobius ] map " " prefix 20 group[ [ "%3s" printf ] each nl ] each`
Output:
```First 199 terms of the Möbius sequence:
1 -1 -1  0 -1  1 -1  0  0  1 -1  0 -1  1  1  0 -1  0 -1
0  1  1 -1  0  0  1  0  0 -1 -1 -1  0  1  1  1  0 -1  1  1
0 -1 -1 -1  0  0  1 -1  0  0  0  1  0 -1  0  1  0  1  1 -1
0 -1  1  0  0  1 -1 -1  0  1 -1 -1  0 -1  1  0  0  1 -1 -1
0  0  1 -1  0  1  1  1  0 -1  0  1  0  1  1  1  0 -1  0  0
0 -1 -1 -1  0 -1  1 -1  0 -1 -1  1  0 -1 -1  1  0  0  1  1
0  0  1  1  0  0  0 -1  0  1 -1 -1  0  1  1  0  0 -1 -1 -1
0  1  1  1  0  1  1  0  0 -1  0 -1  0  0 -1  1  0 -1  1  1
0  1  0 -1  0 -1  1 -1  0  0 -1  0  0 -1 -1  0  0  1  1 -1
0 -1 -1  1  0  1 -1  1  0  0 -1 -1  0 -1  1 -1  0 -1  0 -1
```

## Fortran

Translation of: C
` program moebius    use iso_fortran_env, only: output_unit     integer, parameter          :: mu_max=1000000, line_break=20    integer, parameter          :: sqroot=int(sqrt(real(mu_max)))    integer                     :: i, j    integer, dimension(mu_max)  :: mu     mu = 1     do i = 2, sqroot        if (mu(i) == 1) then            do j = i, mu_max, i                mu(j) = mu(j) * (-i)            end do             do j = i**2, mu_max, i**2                mu(j) = 0            end do        end if    end do     do i = 2, mu_max        if (mu(i) == i) then            mu(i) = 1        else if (mu(i) == -i) then            mu(i) = -1        else if (mu(i) < 0) then            mu(i) = 1        else if (mu(i) > 0) then            mu(i) = -1        end if    end do     write(output_unit,*) "The first 199 terms of the Möbius sequence are:"    write(output_unit,'(3x)', advance="no") ! Alignment of first number    do i = 1, 199        write(output_unit,'(I2,x)', advance="no") mu(i)        if (modulo(i+1, line_break) == 0) write(output_unit,*)    end doend program moebius `
Output:
``` The first 199 terms of the Möbius sequence are:
1 -1 -1  0 -1  1 -1  0  0  1 -1  0 -1  1  1  0 -1  0 -1
0  1  1 -1  0  0  1  0  0 -1 -1 -1  0  1  1  1  0 -1  1  1
0 -1 -1 -1  0  0  1 -1  0  0  0  1  0 -1  0  1  0  1  1 -1
0 -1  1  0  0  1 -1 -1  0  1 -1 -1  0 -1  1  0  0  1 -1 -1
0  0  1 -1  0  1  1  1  0 -1  0  1  0  1  1  1  0 -1  0  0
0 -1 -1 -1  0 -1  1 -1  0 -1 -1  1  0 -1 -1  1  0  0  1  1
0  0  1  1  0  0  0 -1  0  1 -1 -1  0  1  1  0  0 -1 -1 -1
0  1  1  1  0  1  1  0  0 -1  0 -1  0  0 -1  1  0 -1  1  1
0  1  0 -1  0 -1  1 -1  0  0 -1  0  0 -1 -1  0  0  1  1 -1
0 -1 -1  1  0  1 -1  1  0  0 -1 -1  0 -1  1 -1  0 -1  0 -1
```

## FreeBASIC

`function mobius( n as uinteger ) as integer    if n = 1 then return 1    for d as uinteger = 2 to int(sqr(n))        if n mod d = 0 then             if n mod (d*d) = 0 then return 0            return -mobius(n/d)        end if    next d    return -1end function dim as string outstr = " .     "for i as uinteger = 1 to 200    if mobius(i)>=0 then outstr += " "    outstr += str(mobius(i))+"     "    if i mod 10 = 9 then         print outstr        outstr = ""    end ifnext i`
Output:
``` .      1     -1     -1      0     -1      1     -1      0      0
1     -1      0     -1      1      1      0     -1      0     -1
0      1      1     -1      0      0      1      0      0     -1
-1     -1      0      1      1      1      0     -1      1      1
0     -1     -1     -1      0      0      1     -1      0      0
0      1      0     -1      0      1      0      1      1     -1
0     -1      1      0      0      1     -1     -1      0      1
-1     -1      0     -1      1      0      0      1     -1     -1
0      0      1     -1      0      1      1      1      0     -1
0      1      0      1      1      1      0     -1      0      0
0     -1     -1     -1      0     -1      1     -1      0     -1
-1      1      0     -1     -1      1      0      0      1      1
0      0      1      1      0      0      0     -1      0      1
-1     -1      0      1      1      0      0     -1     -1     -1
0      1      1      1      0      1      1      0      0     -1
0     -1      0      0     -1      1      0     -1      1      1
0      1      0     -1      0     -1      1     -1      0      0
-1      0      0     -1     -1      0      0      1      1     -1
0     -1     -1      1      0      1     -1      1      0      0
-1     -1      0     -1      1     -1      0     -1      0     -1```

## FutureBasic

`local fn IsPrime( n as long ) as Boolean  Boolean i, result   if ( n < 2 ) then result = NO : exit fn   for i = 2 to n + 1    if ( i * i <= n ) and ( n mod i == 0 )      result = NO : exit fn    end if  next  result = YESend fn = result local fn Mobius( n as long ) as long  long i, p = 0, result = 0   if ( n == 1 ) then result = 1 : exit fn   for i = 1 to n + 1    if ( n mod i == 0 ) and ( fn IsPrime( i ) == YES )      if ( n mod ( i * i ) == 0 )        result = 0 : exit fn      else        p++      end if    end if  next   if( p mod 2 != 0 )    result = -1  else    result = 1  end ifend fn = result window 1, @"Möbius function", (0,0,600,300) printf @"First 100 terms of Mobius sequence:" long ifor i = 1 to 100  printf @"%2ld\t", fn Mobius(i)  if ( i mod 20 == 0 ) then printnext HandleEvents`
Output:
```First 100 terms of Mobius sequence:
1  -1  -1   0  -1   1  -1   0   0   1  -1   0  -1   1   1   0  -1   0  -1   0
1   1  -1   0   0   1   0   0  -1  -1  -1   0   1   1   1   0  -1   1   1   0
-1  -1  -1   0   0   1  -1   0   0   0   1   0  -1   0   1   0   1   1  -1   0
-1   1   0   0   1  -1  -1   0   1  -1  -1   0  -1   1   0   0   1  -1  -1   0
0   1  -1   0   1   1   1   0  -1   0   1   0   1   1   1   0  -1   0   0   0
```

## Go

`package main import "fmt" func möbius(to int) []int {    if to < 1 {        to = 1    }    mobs := make([]int, to+1) // all zero by default    primes := []int{2}    for i := 1; i <= to; i++ {        j := i        cp := 0      // counts prime factors        spf := false // true if there is a square prime factor        for _, p := range primes {            if p > j {                break            }            if j%p == 0 {                j /= p                cp++            }            if j%p == 0 {                spf = true                break            }        }        if cp == 0 && i > 2 {            cp = 1            primes = append(primes, i)        }        if !spf {            if cp%2 == 0 {                mobs[i] = 1            } else {                mobs[i] = -1            }        }    }    return mobs} func main() {    mobs := möbius(199)    fmt.Println("Möbius sequence - First 199 terms:")    for i := 0; i < 200; i++ {        if i == 0 {            fmt.Print("    ")            continue        }        if i%20 == 0 {            fmt.Println()        }        fmt.Printf("  % d", mobs[i])    }}`
Output:
```Möbius sequence - First 199 terms:
1  -1  -1   0  -1   1  -1   0   0   1  -1   0  -1   1   1   0  -1   0  -1
0   1   1  -1   0   0   1   0   0  -1  -1  -1   0   1   1   1   0  -1   1   1
0  -1  -1  -1   0   0   1  -1   0   0   0   1   0  -1   0   1   0   1   1  -1
0  -1   1   0   0   1  -1  -1   0   1  -1  -1   0  -1   1   0   0   1  -1  -1
0   0   1  -1   0   1   1   1   0  -1   0   1   0   1   1   1   0  -1   0   0
0  -1  -1  -1   0  -1   1  -1   0  -1  -1   1   0  -1  -1   1   0   0   1   1
0   0   1   1   0   0   0  -1   0   1  -1  -1   0   1   1   0   0  -1  -1  -1
0   1   1   1   0   1   1   0   0  -1   0  -1   0   0  -1   1   0  -1   1   1
0   1   0  -1   0  -1   1  -1   0   0  -1   0   0  -1  -1   0   0   1   1  -1
0  -1  -1   1   0   1  -1   1   0   0  -1  -1   0  -1   1  -1   0  -1   0  -1
```

## GW-BASIC

`10 FOR T = 0 TO 920 FOR U = 1 TO 1030 N = 10*T + U40 GOSUB 10050 PRINT USING "##  ";M;60 NEXT U70 PRINT80 NEXT T90 END100 IF N = 1 THEN M = 1 : RETURN110 M = 1 : F = 2120 IF N MOD (F*F) = 0 THEN M = 0 : RETURN130 IF N MOD F = 0 THEN GOSUB 170140 F = F + 1150 IF F <= N THEN GOTO 120160 RETURN170 M = -M180 N = N/F190 RETURN`

`import Data.List (intercalate)import Data.List.Split (chunksOf)import Data.Vector.Unboxed (toList)import Math.NumberTheory.ArithmeticFunctions.Moebius (Moebius(..),                                                      sieveBlockMoebius)import System.Environment (getArgs, getProgName)import System.IO (hPutStrLn, stderr)import Text.Read (readMaybe) -- Calculate the Möbius function, μ(n), for a sequence of values starting at 1.moebiusBlock :: Word -> [Moebius]moebiusBlock = toList . sieveBlockMoebius 1 showMoebiusBlock :: Word -> [Moebius] -> StringshowMoebiusBlock cols = intercalate "\n" . map (concatMap showMoebius) .                        chunksOf (fromIntegral cols)  where showMoebius MoebiusN = " -1"        showMoebius MoebiusZ = "  0"        showMoebius MoebiusP = "  1" main :: IO ()main = do  prog <- getProgName  args <- map readMaybe <\$> getArgs  case args of    [Just cols, Just n] ->      putStrLn ("μ(n) for 1 ≤ n ≤ " ++ show n ++ ":\n") >>      putStrLn (showMoebiusBlock cols \$ moebiusBlock n)    _ -> hPutStrLn stderr \$ "Usage: " ++ prog ++ " num-columns maximum-number"`
Output:
```μ(n) for 1 ≤ n ≤ 200:

1 -1 -1  0 -1  1 -1  0  0  1 -1  0 -1  1  1  0 -1  0 -1  0
1  1 -1  0  0  1  0  0 -1 -1 -1  0  1  1  1  0 -1  1  1  0
-1 -1 -1  0  0  1 -1  0  0  0  1  0 -1  0  1  0  1  1 -1  0
-1  1  0  0  1 -1 -1  0  1 -1 -1  0 -1  1  0  0  1 -1 -1  0
0  1 -1  0  1  1  1  0 -1  0  1  0  1  1  1  0 -1  0  0  0
-1 -1 -1  0 -1  1 -1  0 -1 -1  1  0 -1 -1  1  0  0  1  1  0
0  1  1  0  0  0 -1  0  1 -1 -1  0  1  1  0  0 -1 -1 -1  0
1  1  1  0  1  1  0  0 -1  0 -1  0  0 -1  1  0 -1  1  1  0
1  0 -1  0 -1  1 -1  0  0 -1  0  0 -1 -1  0  0  1  1 -1  0
-1 -1  1  0  1 -1  1  0  0 -1 -1  0 -1  1 -1  0 -1  0 -1  0
```

## J

Implementation:

`mu=: ({{*/1-y>1}} * _1 ^ 2|+/)@q:~&_`

Explanation: _ q: n gives the list of exponents of prime factors of n. (This is an empty list for the number 1, is 2 0 2 for the number 100 and is 3 1 1 for the number 120.)

In this context +/ is the sum of that list, 2 | +/ is 1 if the sum is odd and 0 if the sum is even. _1^0 is 1 and _1^1 is _1. And, {{*/1-y>1}} returns zero if any exponent is at least 2 in magnitude.

`   mu 1+i.10 20 1 _1 _1 0 _1  1 _1 0  0  1 _1 0 _1  1  1 0 _1  0 _1 0 1  1 _1 0  0  1  0 0 _1 _1 _1 0  1  1  1 0 _1  1  1 0_1 _1 _1 0  0  1 _1 0  0  0  1 0 _1  0  1 0  1  1 _1 0_1  1  0 0  1 _1 _1 0  1 _1 _1 0 _1  1  0 0  1 _1 _1 0 0  1 _1 0  1  1  1 0 _1  0  1 0  1  1  1 0 _1  0  0 0_1 _1 _1 0 _1  1 _1 0 _1 _1  1 0 _1 _1  1 0  0  1  1 0 0  1  1 0  0  0 _1 0  1 _1 _1 0  1  1  0 0 _1 _1 _1 0 1  1  1 0  1  1  0 0 _1  0 _1 0  0 _1  1 0 _1  1  1 0 1  0 _1 0 _1  1 _1 0  0 _1  0 0 _1 _1  0 0  1  1 _1 0_1 _1  1 0  1 _1  1 0  0 _1 _1 0 _1  1 _1 0 _1  0 _1 0`

## Java

` public class MöbiusFunction {     public static void main(String[] args) {        System.out.printf("First 199 terms of the möbius function are as follows:%n    ");        for ( int n = 1 ; n < 200 ; n++ ) {            System.out.printf("%2d  ", möbiusFunction(n));            if ( (n+1) % 20 == 0 ) {                System.out.printf("%n");            }        }    }     private static int MU_MAX = 1_000_000;    private static int[] MU = null;     //  Compute mobius function via sieve    private static int möbiusFunction(int n) {        if ( MU != null ) {            return MU[n];        }         //  Populate array        MU = new int[MU_MAX+1];        int sqrt = (int) Math.sqrt(MU_MAX);        for ( int i = 0 ; i < MU_MAX ; i++ ) {            MU[i] = 1;        }         for ( int i = 2 ; i <= sqrt ; i++ ) {            if ( MU[i] == 1 ) {                //  for each factor found, swap + and -                for ( int j = i ; j <= MU_MAX ; j += i ) {                    MU[j] *= -i;                }                //  square factor = 0                for ( int j = i*i ; j <= MU_MAX ; j += i*i ) {                    MU[j] = 0;                }            }        }         for ( int i = 2 ; i <= MU_MAX ; i++ ) {            if ( MU[i] == i ) {                MU[i] = 1;            }            else if ( MU[i] == -i ) {                MU[i] = -1;            }            else if ( MU[i] < 0 ) {                MU[i] = 1;                           }            else if ( MU[i] > 0 ) {                MU[i] = -1;            }        }        return MU[n];    } } `
Output:
```First 199 terms of the möbius function are as follows:
1  -1  -1   0  -1   1  -1   0   0   1  -1   0  -1   1   1   0  -1   0  -1
0   1   1  -1   0   0   1   0   0  -1  -1  -1   0   1   1   1   0  -1   1   1
0  -1  -1  -1   0   0   1  -1   0   0   0   1   0  -1   0   1   0   1   1  -1
0  -1   1   0   0   1  -1  -1   0   1  -1  -1   0  -1   1   0   0   1  -1  -1
0   0   1  -1   0   1   1   1   0  -1   0   1   0   1   1   1   0  -1   0   0
0  -1  -1  -1   0  -1   1  -1   0  -1  -1   1   0  -1  -1   1   0   0   1   1
0   0   1   1   0   0   0  -1   0   1  -1  -1   0   1   1   0   0  -1  -1  -1
0   1   1   1   0   1   1   0   0  -1   0  -1   0   0  -1   1   0  -1   1   1
0   1   0  -1   0  -1   1  -1   0   0  -1   0   0  -1  -1   0   0   1   1  -1
0  -1  -1   1   0   1  -1   1   0   0  -1  -1   0  -1   1  -1   0  -1   0  -1

```

## jq

Works with: jq

Works with gojq, the Go implementation of jq

#### Using a Sieve

`# Input: a non-negative integer, \$n# Output: an array of size \$n + 1 such that the nth-mobius number is .[\$n]# i.e. \$n|mobius_array[-1]# For example, the first mobius number could be evaluated by 1|mobius_array[-1].def mobius_array:  . as \$n  | (\$n|sqrt) as \$sqrt  | reduce range(2; 1 + \$sqrt) as \$i ([range(0; \$n + 1) | 1];       if .[\$i] == 1       then # for each factor found, swap + and -         reduce range(\$i; \$n + 1; \$i) as \$j (.; .[\$j] *= -\$i)          | (\$i*\$i) as \$isq #  square factor = 0         | reduce range(\$isq; \$n + 1; \$isq) as \$j (.; .[\$j] = 0 )       else .       end )  | reduce range(2; 1 + \$n) as \$i (.;       if   .[\$i] ==  \$i then .[\$i] = 1       elif .[\$i] == -\$i then .[\$i] = -1       elif .[\$i]  <   0 then .[\$i] = 1       elif .[\$i]  >   0 then .[\$i] = -1       else .[\$i] = 0                   # avoid "-0"       end); # For one-off computations:def mu(\$n): \$n | mobius_array[-1];`

`def nwise(\$n):  def n: if length <= \$n then . else .[0:\$n] , (.[\$n:] | n) end;  n; def task:  def pp: if . >=0 then " \(.)" else tostring end;  (199 | mobius_array) as \$mu  | "The first 199 Möbius numbers are:",    (["  ", (range(1; 200) | \$mu[.] | pp )]     | nwise(20)     | join(" ") ) ; task`
Output:
```The first 199 Möbius numbers are:
1 -1 -1  0 -1  1 -1  0  0  1 -1  0 -1  1  1  0 -1  0 -1
0  1  1 -1  0  0  1  0  0 -1 -1 -1  0  1  1  1  0 -1  1  1
0 -1 -1 -1  0  0  1 -1  0  0  0  1  0 -1  0  1  0  1  1 -1
0 -1  1  0  0  1 -1 -1  0  1 -1 -1  0 -1  1  0  0  1 -1 -1
0  0  1 -1  0  1  1  1  0 -1  0  1  0  1  1  1  0 -1  0  0
0 -1 -1 -1  0 -1  1 -1  0 -1 -1  1  0 -1 -1  1  0  0  1  1
0  0  1  1  0  0  0 -1  0  1 -1 -1  0  1  1  0  0 -1 -1 -1
0  1  1  1  0  1  1  0  0 -1  0 -1  0  0 -1  1  0 -1  1  1
0  1  0 -1  0 -1  1 -1  0  0 -1  0  0 -1 -1  0  0  1  1 -1
0 -1 -1  1  0  1 -1  1  0  0 -1 -1  0 -1  1 -1  0 -1  0 -1
```

#### Prime Factors

Note that the following solution to the task at hand (computing a range of Mobius numbers is inefficient as it does not cache the primes array. Preliminaries

`# relatively_prime(previous) tests whether the input integer is prime# relative to the primes in the array "previous":def relatively_prime(previous):  . as \$in  | (previous|length) as \$plen  # state: [found, ix]  | [false, 0]  | until( .[0] or .[1] >= \$plen;           [ (\$in % previous[.[1]]) == 0, .[1] + 1] )  | .[0] | not ; # Emit a stream in increasing order of all primes (from 2 onwards)# that are less than or equal to mx:def primes(mx):  # The helper function, next, has arity 0 for tail recursion optimization;  # it expects its input to be the array of previously found primes:  def next:     . as \$previous     | (\$previous | .[length-1]) as \$last     | if (\$last >= mx) then empty       else ((2 + \$last)       | until( relatively_prime(\$previous) ; . + 2)) as \$nextp       | if \$nextp <= mx         then \$nextp, (( \$previous + [\$nextp] ) | next)	 else empty         end       end;  if mx <= 1 then empty  elif mx == 2 then 2  else (2, 3, ([2,3] | next))  end ; # Return an array of the distinct prime factors of . in increasing orderdef prime_factors:   # Return an array of prime factors of . given that "primes"  # is an array of relevant primes:  def pf(\$primes):    if . <= 1 then []    else . as \$in    | if (\$in | relatively_prime(\$primes)) then [\$in]      else reduce \$primes[] as \$p             ([];              if (\$in % \$p) != 0 then . 	      else . + [\$p] +  ((\$in / \$p) | pf(\$primes))	      end)      end      | unique    end;   if . <= 1 then []  else . as \$in  | pf( [ primes( (1+\$in) | sqrt | floor)  ] )  end;`

Mu

`def isSquareFree:  . as \$n  | 2  | until ( (. * . > \$n) or . == 0;       if (\$n % (.*.) == 0) then 0 # i.e. stop       elif . > 2 then . + 2       else . + 1       end  )  | . != 0; def mu:  . as \$n  | if . < 1 then "Argument to mu must be a positive integer" | error    elif . == 1 then 1    else if isSquareFree          then if ((prime_factors|length) % 2 == 0) then 1               else -1              end         else 0         end    end;`

`def nwise(\$n):  def n: if length <= \$n then . else .[0:\$n] , (.[\$n:] | n) end;  n; def task:  def pp: if . >=0 then " \(.)" else tostring end;  "The first 199 Möbius numbers are:",  (["  ", (range(1; 200) | mu | pp )]   | nwise(20)   | join(" ") ) ; task`
Output:

As above.

## Julia

`using Primes # modified from reinermartin's PR at https://github.com/JuliaMath/Primes.jl/pull/70/filesfunction moebius(n::Integer)    @assert n > 0    m(p, e) = p == 0 ? 0 : e == 1 ? -1 : 0    reduce(*, m(p, e) for (p, e) in factor(n) if p ≥ 0; init=1)endμ(n) = moebius(n) print("First 199 terms of the Möbius sequence:\n   ")for n in 1:199    print(lpad(μ(n), 3), n % 20 == 19 ? "\n" : "")end `
Output:
```First 199 terms of the Möbius sequence:
1 -1 -1  0 -1  1 -1  0  0  1 -1  0 -1  1  1  0 -1  0 -1
0  1  1 -1  0  0  1  0  0 -1 -1 -1  0  1  1  1  0 -1  1  1
0 -1 -1 -1  0  0  1 -1  0  0  0  1  0 -1  0  1  0  1  1 -1
0 -1  1  0  0  1 -1 -1  0  1 -1 -1  0 -1  1  0  0  1 -1 -1
0  0  1 -1  0  1  1  1  0 -1  0  1  0  1  1  1  0 -1  0  0
0 -1 -1 -1  0 -1  1 -1  0 -1 -1  1  0 -1 -1  1  0  0  1  1
0  0  1  1  0  0  0 -1  0  1 -1 -1  0  1  1  0  0 -1 -1 -1
0  1  1  1  0  1  1  0  0 -1  0 -1  0  0 -1  1  0 -1  1  1
0  1  0 -1  0 -1  1 -1  0  0 -1  0  0 -1 -1  0  0  1  1 -1
0 -1 -1  1  0  1 -1  1  0  0 -1 -1  0 -1  1 -1  0 -1  0 -1
```

## Kotlin

Translation of: Java
`import kotlin.math.sqrt fun main() {    println("First 199 terms of the möbius function are as follows:")    print("    ")    for (n in 1..199) {        print("%2d  ".format(mobiusFunction(n)))        if ((n + 1) % 20 == 0) {            println()        }    }} private const val MU_MAX = 1000000private var MU: IntArray? = null //  Compute mobius function via sieveprivate fun mobiusFunction(n: Int): Int {    if (MU != null) {        return MU!![n]    }     //  Populate array    MU = IntArray(MU_MAX + 1)    val sqrt = sqrt(MU_MAX.toDouble()).toInt()    for (i in 0 until MU_MAX) {        MU!![i] = 1    }    for (i in 2..sqrt) {        if (MU!![i] == 1) {            //  for each factor found, swap + and -            for (j in i..MU_MAX step i) {                MU!![j] *= -i            }            //  square factor = 0            for (j in i * i..MU_MAX step i * i) {                MU!![j] = 0            }        }    }    for (i in 2..MU_MAX) {        when {            MU!![i] == i -> {                MU!![i] = 1            }            MU!![i] == -i -> {                MU!![i] = -1            }            MU!![i] < 0 -> {                MU!![i] = 1            }            MU!![i] > 0 -> {                MU!![i] = -1            }        }    }    return MU!![n]}`
Output:
```First 199 terms of the möbius function are as follows:
1  -1  -1   0  -1   1  -1   0   0   1  -1   0  -1   1   1   0  -1   0  -1
0   1   1  -1   0   0   1   0   0  -1  -1  -1   0   1   1   1   0  -1   1   1
0  -1  -1  -1   0   0   1  -1   0   0   0   1   0  -1   0   1   0   1   1  -1
0  -1   1   0   0   1  -1  -1   0   1  -1  -1   0  -1   1   0   0   1  -1  -1
0   0   1  -1   0   1   1   1   0  -1   0   1   0   1   1   1   0  -1   0   0
0  -1  -1  -1   0  -1   1  -1   0  -1  -1   1   0  -1  -1   1   0   0   1   1
0   0   1   1   0   0   0  -1   0   1  -1  -1   0   1   1   0   0  -1  -1  -1
0   1   1   1   0   1   1   0   0  -1   0  -1   0   0  -1   1   0  -1   1   1
0   1   0  -1   0  -1   1  -1   0   0  -1   0   0  -1  -1   0   0   1   1  -1
0  -1  -1   1   0   1  -1   1   0   0  -1  -1   0  -1   1  -1   0  -1   0  -1  ```

## Lua

Translation of: C
`function buildArray(size, value)    local tbl = {}    for i=1, size do        table.insert(tbl, value)    end    return tblend MU_MAX = 1000000sqroot = math.sqrt(MU_MAX)mu = buildArray(MU_MAX, 1) for i=2, sqroot do    if mu[i] == 1 then        -- for each factor found, swap + and -        for j=i, MU_MAX, i do            mu[j] = mu[j] * -i        end        -- square factor = 0        for j=i*i, MU_MAX, i*i do            mu[j] = 0        end    endend for i=2, MU_MAX do    if mu[i] == i then        mu[i] = 1    elseif mu[i] == -i then        mu[i] = -1    elseif mu[i] < 0 then        mu[i] = 1    elseif mu[i] > 0 then        mu[i] = -1    endend print("First 199 terms of the mobius function are as follows:")io.write("    ")for i=1, 199 do    io.write(string.format("%2d  ", mu[i]))    if (i + 1) % 20 == 0 then        print()    endend`
Output:
```First 199 terms of the mobius function are as follows:
1  -1  -1   0  -1   1  -1   0   0   1  -1   0  -1   1   1   0  -1   0  -1
0   1   1  -1   0   0   1   0   0  -1  -1  -1   0   1   1   1   0  -1   1   1
0  -1  -1  -1   0   0   1  -1   0   0   0   1   0  -1   0   1   0   1   1  -1
0  -1   1   0   0   1  -1  -1   0   1  -1  -1   0  -1   1   0   0   1  -1  -1
0   0   1  -1   0   1   1   1   0  -1   0   1   0   1   1   1   0  -1   0   0
0  -1  -1  -1   0  -1   1  -1   0  -1  -1   1   0  -1  -1   1   0   0   1   1
0   0   1   1   0   0   0  -1   0   1  -1  -1   0   1   1   0   0  -1  -1  -1
0   1   1   1   0   1   1   0   0  -1   0  -1   0   0  -1   1   0  -1   1   1
0   1   0  -1   0  -1   1  -1   0   0  -1   0   0  -1  -1   0   0   1   1  -1
0  -1  -1   1   0   1  -1   1   0   0  -1  -1   0  -1   1  -1   0  -1   0  -1```

## Mathematica/Wolfram Language

`Grid[Partition[MoebiusMu[Range[99]], UpTo[10]]]`
Output:
```1	-1	-1	0	-1	1	-1	0	0	1
-1	0	-1	1	1	0	-1	0	-1	0
1	1	-1	0	0	1	0	0	-1	-1
-1	0	1	1	1	0	-1	1	1	0
-1	-1	-1	0	0	1	-1	0	0	0
1	0	-1	0	1	0	1	1	-1	0
-1	1	0	0	1	-1	-1	0	1	-1
-1	0	-1	1	0	0	1	-1	-1	0
0	1	-1	0	1	1	1	0	-1	0
1	0	1	1	1	0	-1	0	0	```

## Nim

Uses the prime decomposition method from https://rosettacode.org/wiki/Prime_decomposition#Nim

`import std/[math, sequtils, strformat] func getStep(n: int): int {.inline.} =  result = 1 + n shl 2 - n shr 1 shl 1 func primeFac(n: int): seq[int] =  var     maxq = int(sqrt(float(n)))    d = 1    q: int = 2 + (n and 1)   # Start with 2 or 3 according to oddity.   while q <= maxq and n %% q != 0:    q = getStep(d)    inc d  if q <= maxq:    let q1 = primeFac(n /% q)    let q2 = primeFac(q)    result = concat(q2, q1, result)  else:    result.add(n) func squareFree(num: int): bool =   let fact = primeFac num   for i in fact:    if fact.count(i) > 1:      return false   return true func mobius(num: int): int =   if num == 1: return num   let fact = primeFac num   for i in fact:     ## check if it has a squared prime factor    if fact.count(i) == 2:       return 0   if num.squareFree:    if fact.len mod 2 == 0:       return 1    else:      return -1 when isMainModule:  echo "The first 199 möbius numbers are:"    for i in 1..199:    stdout.write fmt"{mobius(i):4}"    if i mod 20 == 0:      echo "" # print newline `
Output:
```The first 199 möbius numbers are:
1  -1  -1   0  -1   1  -1   0   0   1  -1   0  -1   1   1   0  -1   0  -1   0
1   1  -1   0   0   1   0   0  -1  -1  -1   0   1   1   1   0  -1   1   1   0
-1  -1  -1   0   0   1  -1   0   0   0   1   0  -1   0   1   0   1   1  -1   0
-1   1   0   0   1  -1  -1   0   1  -1  -1   0  -1   1   0   0   1  -1  -1   0
0   1  -1   0   1   1   1   0  -1   0   1   0   1   1   1   0  -1   0   0   0
-1  -1  -1   0  -1   1  -1   0  -1  -1   1   0  -1  -1   1   0   0   1   1   0
0   1   1   0   0   0  -1   0   1  -1  -1   0   1   1   0   0  -1  -1  -1   0
1   1   1   0   1   1   0   0  -1   0  -1   0   0  -1   1   0  -1   1   1   0
1   0  -1   0  -1   1  -1   0   0  -1   0   0  -1  -1   0   0   1   1  -1   0
-1  -1   1   0   1  -1   1   0   0  -1  -1   0  -1   1  -1   0  -1   0  -1   0```

## Pascal

``` See Mertens_function#Pascal
```

## Perl

`use utf8;use strict;use warnings;use feature 'say';use List::Util 'uniq'; sub prime_factors {    my (\$n, \$d, @factors) = (shift, 1);    while (\$n > 1 and \$d++) {        \$n /= \$d, push @factors, \$d until \$n % \$d;    }    @factors} sub μ {    my @p = prime_factors(shift);    @p == uniq(@p) ? 0 == @p%2 ? 1 : -1 : 0;} my @möebius;push @möebius, μ(\$_) for 1 .. (my \$upto = 199); say "Möbius sequence - First \$upto terms:\n" .    (' 'x4 . sprintf "@{['%4d' x \$upto]}", @möebius) =~ s/((.){80})/\$1\n/gr;`
Output:
```Möbius sequence - First 199 terms:
1  -1  -1   0  -1   1  -1   0   0   1  -1   0  -1   1   1   0  -1   0  -1
0   1   1  -1   0   0   1   0   0  -1  -1  -1   0   1   1   1   0  -1   1   1
0  -1  -1  -1   0   0   1  -1   0   0   0   1   0  -1   0   1   0   1   1  -1
0  -1   1   0   0   1  -1  -1   0   1  -1  -1   0  -1   1   0   0   1  -1  -1
0   0   1  -1   0   1   1   1   0  -1   0   1   0   1   1   1   0  -1   0   0
0  -1  -1  -1   0  -1   1  -1   0  -1  -1   1   0  -1  -1   1   0   0   1   1
0   0   1   1   0   0   0  -1   0   1  -1  -1   0   1   1   0   0  -1  -1  -1
0   1   1   1   0   1   1   0   0  -1   0  -1   0   0  -1   1   0  -1   1   1
0   1   0  -1   0  -1   1  -1   0   0  -1   0   0  -1  -1   0   0   1   1  -1
0  -1  -1   1   0   1  -1   1   0   0  -1  -1   0  -1   1  -1   0  -1   0  -1```

## Phix

```with javascript_semantics
function Moebius(integer n)
if n=1 then return 1 end if
sequence f = prime_factors(n,true)
for i=2 to length(f) do
if f[i] = f[i-1] then return 0 end if
end for
return iff(odd(length(f))?-1:+1)
end function

sequence s = {"  ."}
for i=1 to 199 do s = append(s,sprintf("%3d",Moebius(i))) end for
puts(1,join_by(s,1,20," "))
```
Output:
```  .   1  -1  -1   0  -1   1  -1   0   0   1  -1   0  -1   1   1   0  -1   0  -1
0   1   1  -1   0   0   1   0   0  -1  -1  -1   0   1   1   1   0  -1   1   1
0  -1  -1  -1   0   0   1  -1   0   0   0   1   0  -1   0   1   0   1   1  -1
0  -1   1   0   0   1  -1  -1   0   1  -1  -1   0  -1   1   0   0   1  -1  -1
0   0   1  -1   0   1   1   1   0  -1   0   1   0   1   1   1   0  -1   0   0
0  -1  -1  -1   0  -1   1  -1   0  -1  -1   1   0  -1  -1   1   0   0   1   1
0   0   1   1   0   0   0  -1   0   1  -1  -1   0   1   1   0   0  -1  -1  -1
0   1   1   1   0   1   1   0   0  -1   0  -1   0   0  -1   1   0  -1   1   1
0   1   0  -1   0  -1   1  -1   0   0  -1   0   0  -1  -1   0   0   1   1  -1
0  -1  -1   1   0   1  -1   1   0   0  -1  -1   0  -1   1  -1   0  -1   0  -1
```

## Python

Everything verbatim from: https://www.geeksforgeeks.org/program-mobius-function/

All code by: Manish Shaw

Method 1

We iterate through all numbers i smaller than or equal to N. For every number we check if it divides N. If yes, we check if it’s also prime. If both conditions are satisfied, we check if its square also divides N. If yes, we return 0. If the square doesn’t divide, we increment count of prime factors. Finally, we return 1 if there are an even number of prime factors and return -1 if there are odd number of prime factors.

` # Python Program to evaluate# Mobius def M(N) = 1 if N = 1# M(N) = 0 if any prime factor# of N is contained twice# M(N) = (-1)^(no of distinct# prime factors)# Python Program to# evaluate Mobius def# M(N) = 1 if N = 1# M(N) = 0 if any# prime factor of# N is contained twice# M(N) = (-1)^(no of# distinct prime factors) # def to check if# n is prime or notdef isPrime(n) :     if (n < 2) :        return False    for i in range(2, n + 1) :        if (i * i <= n and n % i == 0) :            return False    return True def mobius(N) :     # Base Case    if (N == 1) :        return 1     # For a prime factor i    # check if i^2 is also    # a factor.    p = 0    for i in range(1, N + 1) :        if (N % i == 0 and                isPrime(i)) :             # Check if N is            # divisible by i^2            if (N % (i * i) == 0) :                return 0            else :                 # i occurs only once,                # increase f                p = p + 1     # All prime factors are    # contained only once    # Return 1 if p is even    # else -1    if(p % 2 != 0) :        return -1    else :        return 1 # Driver Codeprint("Mobius numbers from 1..99:") for i in range(1, 100):  print(f"{mobius(i):>4}", end = '')   if i % 20 == 0: print()# This code is contributed by# Manish Shaw(manishshaw1)`
Output:
```Mobius numbers from 1..99:
1  -1  -1   0  -1   1  -1   0   0   1  -1   0  -1   1   1   0  -1   0  -1   0
1   1  -1   0   0   1   0   0  -1  -1  -1   0   1   1   1   0  -1   1   1   0
-1  -1  -1   0   0   1  -1   0   0   0   1   0  -1   0   1   0   1   1  -1   0
-1   1   0   0   1  -1  -1   0   1  -1  -1   0  -1   1   0   0   1  -1  -1   0
0   1  -1   0   1   1   1   0  -1   0   1   0   1   1   1   0  -1   0   0```

Method 2 (Efficient)

The idea is based on efficient program to print all prime factors of a given number. The interesting thing is, we do not need inner while loop here because if a number divides more than once, we can immediately return 0.

`# Python Program to evaluate# Mobius def M(N) = 1 if N = 1# M(N) = 0 if any prime factor# of N is contained twice# M(N) = (-1)^(no of distinct# prime factors)import math # def to check if n# is prime or notdef isPrime(n) :     if (n < 2) :        return False    for i in range(2, n + 1) :        if (n % i == 0) :            return False        i = i * i    return True def mobius(n) :     p = 0     # Handling 2 separately    if (n % 2 == 0) :         n = int(n / 2)        p = p + 1         # If 2^2 also        # divides N        if (n % 2 == 0) :            return 0      # Check for all    # other prime factors    for i in range(3, int(math.sqrt(n)) + 1) :         # If i divides n        if (n % i == 0) :             n = int(n / i)            p = p + 1             # If i^2 also            # divides N            if (n % i == 0) :                return 0        i = i + 2        if(p % 2 == 0) :        return -1    else :        return 1 # Driver Codeprint("Mobius numbers from 1..99:") for i in range(1, 100):  print(f"{mobius(i):>4}", end = '')# This code is contributed by# Manish Shaw(manishshaw1)`
Output:
```Mobius numbers from 1..99:
-1   1  -1   0  -1   1  -1   0   0   1  -1   0  -1   1   1   0  -1   0  -1   0
1   1  -1   0   0   1   0   0  -1  -1  -1   0   1   1   1   0  -1   1   1   0
-1  -1  -1   0   0   1  -1   0   0   0   1   0  -1   0   1   0   1   1  -1   0
-1   1   0   0   1  -1  -1   0   1  -1  -1   0  -1   1   0   0   1  -1  -1   0
0   1  -1   0   1   1   1   0  -1   0   1   0   1   1   1   0  -1   0   0```

## Raku

(formerly Perl 6)

Works with: Rakudo version 2019.11

Möbius number is not defined for n == 0. Raku arrays are indexed from 0 so store a blank value at position zero to keep n and μ(n) aligned.

`use Prime::Factor; sub μ (Int \n) {    return 0 if n %% 4 or n %% 9 or n %% 25 or n %% 49 or n %% 121;    my @p = prime-factors(n);    +@p == +@p.unique ?? +@p %% 2 ?? 1 !! -1 !! 0} my @möbius = lazy flat '', 1, (2..*).hyper.map: -> \n { μ(n) }; # The Taskput "Möbius sequence - First 199 terms:\n",    @möbius[^200]».fmt('%3s').batch(20).join: "\n";`
Output:
```Möbius sequence - First 199 terms:
1  -1  -1   0  -1   1  -1   0   0   1  -1   0  -1   1   1   0  -1   0  -1
0   1   1  -1   0   0   1   0   0  -1  -1  -1   0   1   1   1   0  -1   1   1
0  -1  -1  -1   0   0   1  -1   0   0   0   1   0  -1   0   1   0   1   1  -1
0  -1   1   0   0   1  -1  -1   0   1  -1  -1   0  -1   1   0   0   1  -1  -1
0   0   1  -1   0   1   1   1   0  -1   0   1   0   1   1   1   0  -1   0   0
0  -1  -1  -1   0  -1   1  -1   0  -1  -1   1   0  -1  -1   1   0   0   1   1
0   0   1   1   0   0   0  -1   0   1  -1  -1   0   1   1   0   0  -1  -1  -1
0   1   1   1   0   1   1   0   0  -1   0  -1   0   0  -1   1   0  -1   1   1
0   1   0  -1   0  -1   1  -1   0   0  -1   0   0  -1  -1   0   0   1   1  -1
0  -1  -1   1   0   1  -1   1   0   0  -1  -1   0  -1   1  -1   0  -1   0  -1```

## REXX

Note that the   Möbius   function is also spelled   Mobius   and/or   Moebius,   and it is also known as the   mu   function,   where   mu   is the Greek symbol   μ.

Programming note:   This REXX version supports the specifying of the low and high values to be generated,
as well as the group size for the grid   (it can be specified as   1   which will show a vertical list).

A null value will be shown as a bullet (•) when showing the Möbius value of for zero   (this can be changed in the 2nd line of the   mobius   function).

The above "feature" was added to make the grid to be aligned with other solutions.

The function to computer some prime numbers is a bit of an overkill, but the goal was to keep it general  (in case of larger/higher ranges for a Möbius sequence).

`/*REXX pgm computes & shows a value grid of the Möbius function for a range of integers.*/parse arg LO HI grp .                            /*obtain optional arguments from the CL*/if  LO=='' |  LO==","  then  LO=   0             /*Not specified?  Then use the default.*/if  HI=='' |  HI==","  then  HI= 199             /* "      "         "   "   "     "    */if grp=='' | grp==","  then grp=  20             /* "      "         "   "   "     "    */                                                 /*                            ______   */call genP HI                                     /*generate primes up to the  √  HI     */say center(' The Möbius sequence from ' LO " ──► " HI" ", max(50, grp*3), '═')   /*title*/\$=                                               /*variable holds output grid of GRP #s.*/    do j=LO  to  HI;  \$= \$  right( mobius(j), 2) /*process some numbers from  LO ──► HI.*/    if words(\$)==grp  then do;  say substr(\$, 2);  \$=    /*show grid if fully populated,*/                           end                           /*  and nullify it for more #s.*/    end   /*j*/                                  /*for small grids, using wordCnt is OK.*/ if \$\==''  then say substr(\$, 2)                 /*handle any residual numbers not shown*/exit                                             /*stick a fork in it,  we're all done. *//*──────────────────────────────────────────────────────────────────────────────────────*/mobius: procedure expose @.;  parse arg x        /*obtain a integer to be tested for mu.*/        if x<1  then return '∙'                  /*special? Then return symbol for null.*/        #= 0                                     /*start with a value of zero.          */             do k=1;  p= @.k                     /*get the  Kth  (pre─generated)  prime.*/             if p>x  then leave                  /*prime (P)   > X?    Then we're done. */             if p*p>x  then do;   #= #+1;  leave /*prime (P**2 > X?    Bump # and leave.*/                            end             if x//p==0  then do; #= #+1         /*X divisible by P?   Bump mu number.  */                                  x= x % p       /*                    Divide by prime. */                                  if x//p==0  then return 0  /*X÷by P?  Then return zero*/                              end             end   /*k*/                         /*#  (below) is almost always small, <9*/        if #//2==0  then return  1               /*Is # even?   Then return postive  1  */                         return -1               /* " "  odd?     "     "   negative 1. *//*──────────────────────────────────────────────────────────────────────────────────────*/genP: @.1=2; @.2=3; @.3=5; @.4=7; @.5=11; @.6= 13;  nP=6  /*assign low primes; # primes.*/                    do lim=nP  until lim*lim>=HI /*only keep primes up to the  sqrt(HI).*/                    end   /*lim*/       do [email protected].nP+4  by 2  to HI                  /*only find odd primes from here on.   */       parse var j '' -1 _;if _==5  then iterate /*Is last digit a "5"?   Then not prime*/       if j// 3==0  then iterate                 /*is J divisible by  3?    "   "    "  */       if j// 7==0  then iterate                 /* " "     "      "  7?    "   "    "  */       if j//11==0  then iterate                 /* " "     "      " 11?    "   "    "  */       if j//13==0  then iterate                 /* " "     "      " 13?    "   "    "  */                 do k=7  while k*k<=j            /*divide by some generated odd primes. */                 if j // @.k==0  then iterate j  /*Is J divisible by  P?  Then not prime*/                 end   /*k*/                     /* [↓]  a prime  (J)  has been found.  */       nP= nP+1;    if nP<=HI  then @.nP= j      /*bump prime count; assign prime to  @.*/       end      /*j*/;              return`
output   when using the default inputs:

Output note:   note the use of a bullet (•) to signify that a "null" is being shown (for the 0th entry).

```══════════ The Möbius sequence from  0  ──►  199 ═══════════
∙  1 -1 -1  0 -1  1 -1  0  0  1 -1  0 -1  1  1  0 -1  0 -1
0  1  1 -1  0  0  1  0  0 -1 -1 -1  0  1  1  1  0 -1  1  1
0 -1 -1 -1  0  0  1 -1  0  0  0  1  0 -1  0  1  0  1  1 -1
0 -1  1  0  0  1 -1 -1  0  1 -1 -1  0 -1  1  0  0  1 -1 -1
0  0  1 -1  0  1  1  1  0 -1  0  1  0  1  1  1  0 -1  0  0
0 -1 -1 -1  0 -1  1 -1  0 -1 -1  1  0 -1 -1  1  0  0  1  1
0  0  1  1  0  0  0 -1  0  1 -1 -1  0  1  1  0  0 -1 -1 -1
0  1  1  1  0  1  1  0  0 -1  0 -1  0  0 -1  1  0 -1  1  1
0  1  0 -1  0 -1  1 -1  0  0 -1  0  0 -1 -1  0  0  1  1 -1
0 -1 -1  1  0  1 -1  1  0  0 -1 -1  0 -1  1 -1  0 -1  0 -1
```

## Ring

Translation of: FreeBASIC
` mobStr = "      . " for i = 1 to 200    if mobius(i) >= 0       mobStr + = " "    ok    temp = string(mobius(i))    if left(temp,2) = "-0"       temp = right(temp,len(temp)-1)    ok    mobStr += temp + " "    if i % 10 = 9          see mobStr + nl        mobStr = "     "    oknext func mobius(n)     if n = 1         return 1     ok     for d = 2 to ceil(sqrt(n))         if n % d = 0              if n % (d*d) = 0               return 0            ok            return -mobius(n/d)         ok     next      return -1 `

Output:

```      .  1 -1 -1  0 -1  1 -1  0  0
1 -1  0 -1  1  1  0 -1  0 -1
0  1  1 -1  0  0  1  0  0 -1
-1 -1  0  1  1  1  0 -1  1  1
0 -1 -1 -1  0  0  1 -1  0  0
0  1  0 -1  0  1  0  1  1 -1
0 -1  1  0  0  1 -1 -1  0  1
-1 -1  0 -1  1  0  0  1 -1 -1
0  0  1 -1  0  1  1  1  0 -1
0  1  0  1  1  1  0 -1  0  0
0 -1 -1 -1  0 -1  1 -1  0 -1
-1  1  0 -1 -1  1  0  0  1  1
0  0  1  1  0  0  0 -1  0  1
-1 -1  0  1  1  0  0 -1 -1 -1
0  1  1  1  0  1  1  0  0 -1
0 -1  0  0 -1  1  0 -1  1  1
0  1  0 -1  0 -1  1 -1  0  0
-1  0  0 -1 -1  0  0  1  1 -1
0 -1 -1  1  0  1 -1  1  0  0
-1 -1  0 -1  1 -1  0 -1  0 -1
```

## Ruby

`require 'prime' def μ(n)  pd = n.prime_division  return 0 unless pd.map(&:last).all?(1)  pd.size.even? ? 1 : -1end (["  "] + (1..199).map{|n|"%2s" % μ(n)}).each_slice(20){|line| puts line.join(" ") }  `
Output:
```    1 -1 -1  0 -1  1 -1  0  0  1 -1  0 -1  1  1  0 -1  0 -1
0  1  1 -1  0  0  1  0  0 -1 -1 -1  0  1  1  1  0 -1  1  1
0 -1 -1 -1  0  0  1 -1  0  0  0  1  0 -1  0  1  0  1  1 -1
0 -1  1  0  0  1 -1 -1  0  1 -1 -1  0 -1  1  0  0  1 -1 -1
0  0  1 -1  0  1  1  1  0 -1  0  1  0  1  1  1  0 -1  0  0
0 -1 -1 -1  0 -1  1 -1  0 -1 -1  1  0 -1 -1  1  0  0  1  1
0  0  1  1  0  0  0 -1  0  1 -1 -1  0  1  1  0  0 -1 -1 -1
0  1  1  1  0  1  1  0  0 -1  0 -1  0  0 -1  1  0 -1  1  1
0  1  0 -1  0 -1  1 -1  0  0 -1  0  0 -1 -1  0  0  1  1 -1
0 -1 -1  1  0  1 -1  1  0  0 -1 -1  0 -1  1 -1  0 -1  0 -1
```

## Sidef

Built-in:

`say moebius(53)    #=> -1say moebius(54)    #=> 0say moebius(55)    #=> 1`

Simple implementation:

`func μ(n) {    var f = n.factor_exp.map { .tail }    f.any { _ > 1 } ? 0 : ((-1)**f.sum)} with (199) { |n|    say "Values of the Möbius function for numbers in the range 1..#{n}:"    [' '] + (1..n->map(μ)) -> each_slice(20, {|*line|        say line.map { '%2s' % _ }.join(' ')    })}`
Output:
```Values of the Möbius function for numbers in the range 1..199:
1 -1 -1  0 -1  1 -1  0  0  1 -1  0 -1  1  1  0 -1  0 -1
0  1  1 -1  0  0  1  0  0 -1 -1 -1  0  1  1  1  0 -1  1  1
0 -1 -1 -1  0  0  1 -1  0  0  0  1  0 -1  0  1  0  1  1 -1
0 -1  1  0  0  1 -1 -1  0  1 -1 -1  0 -1  1  0  0  1 -1 -1
0  0  1 -1  0  1  1  1  0 -1  0  1  0  1  1  1  0 -1  0  0
0 -1 -1 -1  0 -1  1 -1  0 -1 -1  1  0 -1 -1  1  0  0  1  1
0  0  1  1  0  0  0 -1  0  1 -1 -1  0  1  1  0  0 -1 -1 -1
0  1  1  1  0  1  1  0  0 -1  0 -1  0  0 -1  1  0 -1  1  1
0  1  0 -1  0 -1  1 -1  0  0 -1  0  0 -1 -1  0  0  1  1 -1
0 -1 -1  1  0  1 -1  1  0  0 -1 -1  0 -1  1 -1  0 -1  0 -1
```

## Tiny BASIC

Tiny BASIC is not suited for printing tables, so this is limited to prompting for a single number and calculating its Mobius number.

`    PRINT "Enter an integer"    INPUT N    IF N < 0 THEN LET N = -N    IF N < 2 THEN GOTO 100 + N    LET C = 1    LET F = 2 10 IF ((N/F)/F)*F*F = N THEN GOTO 100    IF (N/F)*F = N THEN GOTO 30 20 LET F = F + 1    IF F<=N THEN GOTO 10    GOTO 100 + C 30 LET N = N / F    LET C = -C    GOTO 20 99 PRINT "-1"    END100 PRINT "0"    END101 PRINT "1"    END`

## Wren

Library: Wren-fmt
Library: Wren-math
`import "/fmt" for Fmtimport "/math" for Int var isSquareFree = Fn.new { |n|    var i = 2    while (i * i <= n) {        if (n%(i*i) == 0) return false        i = (i > 2) ? i + 2 : i + 1    }    return true} var mu = Fn.new { |n|    if (n < 1) Fiber.abort("Argument must be a positive integer")    if (n == 1) return 1    var sqFree = isSquareFree.call(n)    var factors = Int.primeFactors(n)    if (sqFree && factors.count % 2 == 0) return 1    if (sqFree) return -1    return 0} System.print("The first 199 Möbius numbers are:")for (i in 0..9) {    for (j in 0..19) {        if (i == 0 && j == 0) {            System.write("    ")        } else {            System.write("%(Fmt.dm(3, mu.call(i*20 + j))) ")        }    }    System.print()}`
Output:
```The first 199 Möbius numbers are:
1  -1  -1   0  -1   1  -1   0   0   1  -1   0  -1   1   1   0  -1   0  -1
0   1   1  -1   0   0   1   0   0  -1  -1  -1   0   1   1   1   0  -1   1   1
0  -1  -1  -1   0   0   1  -1   0   0   0   1   0  -1   0   1   0   1   1  -1
0  -1   1   0   0   1  -1  -1   0   1  -1  -1   0  -1   1   0   0   1  -1  -1
0   0   1  -1   0   1   1   1   0  -1   0   1   0   1   1   1   0  -1   0   0
0  -1  -1  -1   0  -1   1  -1   0  -1  -1   1   0  -1  -1   1   0   0   1   1
0   0   1   1   0   0   0  -1   0   1  -1  -1   0   1   1   0   0  -1  -1  -1
0   1   1   1   0   1   1   0   0  -1   0  -1   0   0  -1   1   0  -1   1   1
0   1   0  -1   0  -1   1  -1   0   0  -1   0   0  -1  -1   0   0   1   1  -1
0  -1  -1   1   0   1  -1   1   0   0  -1  -1   0  -1   1  -1   0  -1   0  -1
```

## XPL0

`func Mobius(N);int  N, Cnt, F, K;[Cnt:= 0;F:= 2;  K:= 0;repeat  if rem(N/F) = 0 then                [Cnt:= Cnt+1;                N:= N/F;                K:= K+1;                if K >= 2 then return 0;                ]        else    [F:= F+1;  K:= 0];until   F > N;return if Cnt&1 then -1 else 1;]; int  N;[Format(3, 0);Text(0, "   ");for N:= 1 to 199 do        [RlOut(0, float(Mobius(N)));        if rem(N/20) = 19 then CrLf(0);        ];]`
Output:
```     1 -1 -1  0 -1  1 -1  0  0  1 -1  0 -1  1  1  0 -1  0 -1
0  1  1 -1  0  0  1  0  0 -1 -1 -1  0  1  1  1  0 -1  1  1
0 -1 -1 -1  0  0  1 -1  0  0  0  1  0 -1  0  1  0  1  1 -1
0 -1  1  0  0  1 -1 -1  0  1 -1 -1  0 -1  1  0  0  1 -1 -1
0  0  1 -1  0  1  1  1  0 -1  0  1  0  1  1  1  0 -1  0  0
0 -1 -1 -1  0 -1  1 -1  0 -1 -1  1  0 -1 -1  1  0  0  1  1
0  0  1  1  0  0  0 -1  0  1 -1 -1  0  1  1  0  0 -1 -1 -1
0  1  1  1  0  1  1  0  0 -1  0 -1  0  0 -1  1  0 -1  1  1
0  1  0 -1  0 -1  1 -1  0  0 -1  0  0 -1 -1  0  0  1  1 -1
0 -1 -1  1  0  1 -1  1  0  0 -1 -1  0 -1  1 -1  0 -1  0 -1
```

## Yabasic

Translation of: FreeBASIC
`outstr\$ = " .  "for i = 1 to 200    if mobius(i) >= 0 then outstr\$ = outstr\$ + " " : fi    outstr\$ = outstr\$ + str\$(mobius(i)) + "  "    if mod(i, 10) = 9 then         print outstr\$        outstr\$ = ""    end ifnext iend sub mobius(n)    if n = 1 then return 1 : fi    for d = 2 to int(sqr(n))        if mod(n, d) = 0 then             if mod(n, (d*d)) = 0 then return 0 : fi            return -mobius(n/d)        end if    next d    return -1end sub`

## zkl

`fcn mobius(n){   pf:=primeFactors(n);   sq:=pf.filter1('wrap(f){ (n % (f*f))==0 });  // False if square free   if(sq==False){ if(pf.len().isEven) 1 else -1 }   else 0}fcn primeFactors(n){  // Return a list of prime factors of n   acc:=fcn(n,k,acc,maxD){  // k is 2,3,5,7,9,... not optimum      if(n==1 or k>maxD) acc.close();      else{	 q,r:=n.divr(k);   // divr-->(quotient,remainder)	 if(r==0) return(self.fcn(q,k,acc.write(k),q.toFloat().sqrt()));	 return(self.fcn(n,k+1+k.isOdd,acc,maxD))  # both are tail recursion      }   }(n,2,Sink(List),n.toFloat().sqrt());   m:=acc.reduce('*,1);      // mulitply factors   if(n!=m) acc.append(n/m); // opps, missed last factor   else acc;}`
`[1..199].apply(mobius).pump(Console.println, T(Void.Read,19,False),	fcn{ vm.arglist.pump(String,"%3d".fmt) });`
Output:
```  1 -1 -1  0 -1  1 -1  0  0  1 -1  0 -1  1  1  0 -1  0 -1  0
1  1 -1  0  0  1  0  0 -1 -1 -1  0  1  1  1  0 -1  1  1  0
-1 -1 -1  0  0  1 -1  0  0  0  1  0 -1  0  1  0  1  1 -1  0
-1  1  0  0  1 -1 -1  0  1 -1 -1  0 -1  1  0  0  1 -1 -1  0
0  1 -1  0  1  1  1  0 -1  0  1  0  1  1  1  0 -1  0  0  0
-1 -1 -1  0 -1  1 -1  0 -1 -1  1  0 -1 -1  1  0  0  1  1  0
0  1  1  0  0  0 -1  0  1 -1 -1  0  1  1  0  0 -1 -1 -1  0
1  1  1  0  1  1  0  0 -1  0 -1  0  0 -1  1  0 -1  1  1  0
1  0 -1  0 -1  1 -1  0  0 -1  0  0 -1 -1  0  0  1  1 -1  0
-1 -1  1  0  1 -1  1  0  0 -1 -1  0 -1  1 -1  0 -1  0 -1
```