Radical of an integer
You are encouraged to solve this task according to the task description, using any language you may know.
- Definition
The radical of a positive integer is defined as the product of its distinct prime factors.
Although the integer 1 has no prime factors, its radical is regarded as 1 by convention.
- Example
The radical of 504 = 2³ x 3² x 7 is: 2 x 3 x 7 = 42.
- Task
1. Find and show on this page the radicals of the first 50 positive integers.
2. Find and show the radicals of the integers: 99999, 499999 and 999999.
3. By considering their radicals, show the distribution of the first one million positive integers by numbers of distinct prime factors (hint: the maximum number of distinct factors is 7).
- Bonus
By (preferably) using an independent method, calculate the number of primes and the number of powers of primes less than or equal to one million and hence check that your answer in 3. above for numbers with one distinct prime is correct.
- Related tasks
- References
- Wikipedia article Radical of an integer
- OEIS sequence A007947: Largest square free number dividing n
C
#include <stdio.h>
int radical(int num, int *dps_out) {
int rad = 1, dps = 0, div;
if ((num & 1) == 0) {
while ((num & 1) == 0) num >>= 1;
rad *= 2;
dps++;
}
for (div = 3; div <= num; div += 2) {
if (num % div != 0) continue;
rad *= div;
dps++;
while (num % div == 0) num /= div;
}
if (dps_out != NULL) *dps_out = dps;
return rad;
}
void show_first_50() {
int n;
printf("Radicals of 1..50:\n");
for (n = 1; n <= 50; n++) {
printf("%5d", radical(n, NULL));
if (n % 5 == 0) printf("\n");
}
}
void show_rad(int n) {
printf("The radical of %d is %d.\n", n, radical(n, NULL));
}
void find_distribution() {
int n, dps, dist[8] = {0};
for (n = 1; n <= 1000000; n++) {
printf("%d\r", n);
radical(n, &dps);
dist[dps]++;
}
printf("Distribution of radicals:\n");
for (dps = 0; dps < 8; dps++) {
printf("%d: %d\n", dps, dist[dps]);
}
}
int main() {
show_first_50();
printf("\n");
show_rad(99999);
show_rad(499999);
show_rad(999999);
printf("\n");
find_distribution();
return 0;
}
- Output:
Radicals of 1..50: 1 2 3 2 5 6 7 2 3 10 11 6 13 14 15 2 17 6 19 10 21 22 23 6 5 26 3 14 29 30 31 2 33 34 35 6 37 38 39 10 41 42 43 22 15 46 47 6 7 10 The radical of 99999 is 33333. The radical of 499999 is 3937. The radical of 999999 is 111111. Distribution of radicals: 0: 1 1: 78734 2: 288726 3: 379720 4: 208034 5: 42492 6: 2285 7: 8
CLU
distinct_factors = iter (n: int) yields (int)
if n // 2 = 0 then
yield(2)
while n // 2 = 0 do n := n / 2 end
end
div: int := 3
while div <= n do
if n // div = 0 then
yield(div)
while n // div = 0 do n := n / div end
end
div := div + 2
end
end distinct_factors
radical = proc (n: int) returns (int)
rad: int := 1
for fac: int in distinct_factors(n) do
rad := rad * fac
end
return(rad)
end radical
dpf_count = proc (n: int) returns (int)
count: int := 0
for fac: int in distinct_factors(n) do
count := count + 1
end
return(count)
end dpf_count
show_first_50 = proc (out: stream)
stream$putl(out, "Radicals of 1..50:")
for n: int in int$from_to(1, 50) do
stream$putright(out, int$unparse(radical(n)), 5)
if n // 10 = 0 then stream$putl(out, "") end
end
end show_first_50
show_radical = proc (out: stream, n: int)
stream$puts(out, "The radical of ")
stream$puts(out, int$unparse(n))
stream$puts(out, " is ")
stream$puts(out, int$unparse(radical(n)))
stream$putl(out, ".")
end show_radical
find_distribution = proc (out: stream)
dist: array[int] := array[int]$fill(0, 8, 0)
for n: int in int$from_to(1, 1000000) do
stream$putright(out, int$unparse(n) || "\r", 8)
dpf: int := dpf_count(n)
dist[dpf] := dist[dpf] + 1
end
stream$putl(out, "Distribution of radicals:")
for dpf: int in array[int]$indexes(dist) do
stream$putright(out, int$unparse(dpf), 1)
stream$puts(out, ": ")
stream$putright(out, int$unparse(dist[dpf]), 8)
stream$putl(out, "")
end
end find_distribution
start_up = proc ()
po: stream := stream$primary_output()
show_first_50(po)
stream$putl(po, "")
for n: int in array[int]$elements(array[int]$[99999, 499999, 999999]) do
show_radical(po, n)
end
stream$putl(po, "")
find_distribution(po)
end start_up
- Output:
Radicals of 1..50: 1 2 3 2 5 6 7 2 3 10 11 6 13 14 15 2 17 6 19 10 21 22 23 6 5 26 3 14 29 30 31 2 33 34 35 6 37 38 39 10 41 42 43 22 15 46 47 6 7 10 The radical of 99999 is 33333. The radical of 499999 is 3937. The radical of 999999 is 111111. Distribution of radicals: 0: 1 1: 78734 2: 288726 3: 379720 4: 208034 5: 42492 6: 2285 7: 8
Cowgol
include "cowgol.coh";
sub radical(n: uint32): (rad: uint32, dpf: uint8) is
dpf := 0;
rad := 1;
# Handle factors of 2 first
if n & 1 == 0 then
dpf := 1;
rad := 2;
while n > 0 and n & 1 == 0 loop
n := n >> 1;
end loop;
end if;
# Divide out odd prime factors
var div: uint32 := 3;
while div <= n loop
if n % div == 0 then
dpf := dpf + 1;
rad := rad * div;
while n % div == 0 loop
n := n / div;
end loop;
end if;
div := div + 2;
end loop;
end sub;
sub first50() is
print("Radicals of 1..50:\n");
var n: uint32 := 1;
var dpf: uint8;
var rad: uint32;
while n <= 50 loop
(rad, dpf) := radical(n);
print_i32(rad);
if n % 5 != 0 then
print_char('\t');
else
print_nl();
end if;
n := n + 1;
end loop;
end sub;
sub print_rad(n: uint32) is
var dpf: uint8;
var rad: uint32;
print("The radical of ");
print_i32(n);
print(" is ");
(rad, dpf) := radical(n);
print_i32(rad);
print(".\n");
end sub;
sub find_distribution() is
var dist: uint32[8];
MemZero(&dist[0] as [uint8], @bytesof dist);
var n: uint32 := 1;
var dpf: uint8;
var rad: uint32;
while n <= 1000000 loop
print_i32(n);
print_char('\r');
(rad, dpf) := radical(n);
dist[dpf] := dist[dpf] + 1;
n := n + 1;
end loop;
print("Distribution of radicals:\n");
dpf := 0;
while dpf < 8 loop
print_i8(dpf);
print(": ");
print_i32(dist[dpf]);
print_nl();
dpf := dpf + 1;
end loop;
end sub;
first50();
print_nl();
print_rad(99999);
print_rad(499999);
print_rad(999999);
print_nl();
find_distribution();
- Output:
Radicals of 1..50: 1 2 3 2 5 6 7 2 3 10 11 6 13 14 15 2 17 6 19 10 21 22 23 6 5 26 3 14 29 30 31 2 33 34 35 6 37 38 39 10 41 42 43 22 15 46 47 6 7 10 The radical of 99999 is 33333. The radical of 499999 is 3937. The radical of 999999 is 111111. Distribution of radicals: 0: 1 1: 78734 2: 288726 3: 379720 4: 208034 5: 42492 6: 2285 7: 8
FreeBASIC
'#include "isprime.bas"
Function Radical(n As Integer) As Integer 'Return radical of n
Dim As Integer d = 2, d0 = 0, p = 1
While n >= d*d
While n Mod d = 0
If d <> d0 Then
p *= d
d0 = d
End If
n /= d
Wend
d += 1
Wend
If d <> d0 Then p *= n
Return p
End Function
Function DistinctFactors(n As Integer) As Integer 'Return count of distinct factors of n
Dim As Integer d = 2, d0 = 0, c = 0
While n >= d*d
While n Mod d = 0
If d <> d0 Then
c += 1
d0 = d
End If
n = n/d
Wend
d += 1
Wend
If d <> d0 And n <> 1 Then c += 1
Return c
End Function
Dim As Integer n, c, count(0 To 9), pcount, ppcount, p2, p
Print "The radicals for the first 50 positive integers are:"
For n = 1 To 50
Print Using "####"; Radical(n);
If n Mod 10 = 0 Then Print
Next
Print Using !"\nRadical for ###,###: ###,###"; 99999; Radical(99999)
Print Using "Radical for ###,###: ###,###"; 499999; Radical(499999)
Print Using "Radical for ###,###: ###,###"; 999999; Radical(999999)
For n = 0 To 9
count(n) = 0
Next
For n = 1 To 1e6
c = DistinctFactors(n)
count(c) += 1
Next
Print !"\nBreakdown of numbers of distinct prime factors \nfor positive integers from 1 to 1,000,000:"
c = 0
For n = 0 To 9
If count(n) > 0 Then Print Using " #: ###,###"; n; count(n)
c += count(n)
Next
Print Using !" ---------\n #,###,###"; c
Print !"\nor graphically:\n"; String(50, "-")
For n = 0 To 9
If count(n) > 0 Then Print n; " "; String(count(n)/1e4, Chr(177)); " "; count(n)
c += count(n)
Next
Print String(50, "-")
'Bonus (algorithm from Wren):
pcount = 0
For n = 1 To 1e6
If isPrime(n) Then pcount += 1
Next
Print !"\nFor primes or powers (>1) thereof <= 1,000,000:"
Print Using " Number of primes: ##,###"; pcount
ppcount = 0
For p = 1 To Sqr(1e6)
If isPrime(p) Then
p2 = p
Do
p2 *= p
If p2 > 1e6 Then Exit Do
ppcount += 1
Loop
End If
Next
Print Using " Number of powers: ##,###"; ppcount
Print Using "Add 1 for number 1: ##,###"; 1
If isPrime(n) Then pcount += 1
Print Spc(19); "-------"
Print Spc(13); Using !"Total: ##,###"; pcount + ppcount + 1
Sleep
- Output:
The radicals for the first 50 positive integers are: 1 2 3 2 5 6 7 2 3 10 11 6 13 14 15 2 17 6 19 10 21 22 23 6 5 26 3 14 29 30 31 2 33 34 35 6 37 38 39 10 41 42 43 22 15 46 47 6 7 10 Radical for 99,999: 33,333 Radical for 499,999: 3,937 Radical for 999,999: 111,111 Breakdown of numbers of distinct prime factors for positive integers from 1 to 1,000,000: 0: 1 1: 78,734 2: 288,726 3: 379,720 4: 208,034 5: 42,492 6: 2,285 7: 8 --------- 1,000,000 or graphically: -------------------------------------------------- 0 1 1 ▒▒▒▒▒▒▒▒ 78734 2 ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ 288726 3 ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ 379720 4 ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒ 208034 5 ▒▒▒▒ 42492 6 2285 7 8 -------------------------------------------------- For primes or powers (>1) thereof <= 1,000,000: Number of primes: 78,498 Number of powers: 236 Add 1 for number 1: 1 ------- Total: 78,735
J
~.&.q: 1+i.5 10 NB. radicals of first 50 positive integers
1 2 3 2 5 6 7 2 3 10
11 6 13 14 15 2 17 6 19 10
21 22 23 6 5 26 3 14 29 30
31 2 33 34 35 6 37 38 39 10
41 42 43 22 15 46 47 6 7 10
~.&.q: 99999 499999 999999 NB. radicals of these three...
33333 3937 111111
(~.,.#/.~) 1>.#@~.@q: 1+i.1e6 NB. distribution of number of prime factors of first million positive integers
1 78735
2 288726
3 379720
4 208034
5 42492
6 2285
7 8
p:inv 1e6 NB. number of primes not exceeding 1 million
78498
+/_1+<.(i.&.(p:inv) 1000)^.1e6 NB. count of prime powers (square or above) up to 1 million
236
78498+236+1 NB. and we "claimed" that 1 had a prime factor
78735
jq
Adapted from Wren
Also works with gojq, the Go implementations of jq, except that gojq is likely to run out of memory before completing part2.
# Utility functions
def lpad($len): tostring | ($len - length) as $l | (" " * $l) + .;
def prod(s): reduce s as $x (1; . * $x);
def sum(s): reduce s as $x (0; . + $x);
def uniq(s):
foreach s as $x (null;
if . and $x == .[0] then .[1] = false
else [$x, true]
end;
if .[1] then .[0] else empty end);
# Prime number functions
# Returns the prime factors of . in order using a wheel with basis [2, 3, 5].
def primeFactors:
def out($i): until (.n % $i != 0; .factors += [$i] | .n = ((.n/$i)|floor) );
if . < 2 then []
else [4, 2, 4, 2, 4, 6, 2, 6] as $inc
| { n: .,
factors: [] }
| out(2)
| out(3)
| out(5)
| .k = 7
| .i = 0
| until(.k * .k > .n;
if .n % .k == 0
then .factors += [.k]
| .n = ((.n/.k)|floor)
else .k += $inc[.i]
| .i = ((.i + 1) % 8)
end)
| if .n > 1 then .factors += [.n] else . end
| .factors
end;
# Input: a positive integer
# Output: an array, $a, of length .+1 such that
# $a[$i] is $i if $i is prime, and false otherwise.
def primeSieve:
# erase(i) sets .[i*j] to false for integral j > 1
def erase($i):
if .[$i] then
reduce (range(2*$i; length; $i)) as $j (.; .[$j] = false)
else .
end;
(. + 1) as $n
| (($n|sqrt) / 2) as $s
| [null, null, range(2; $n)]
| reduce (2, 1 + (2 * range(1; $s))) as $i (.; erase($i)) ;
# Number of primes up to and including .
def primeCount:
sum(primeSieve[] | select(.) | 1);
## Radicals
def task1:
{ radicals: [0],
counts: [range(0;8)|0] }
| .radicals[1] = 1
| .counts[1] = 1
| foreach range(2; 1+1e6) as $i (.;
.factors = [uniq($i|primeFactors[])]
| (.factors|length) as $fc
| .counts[$fc] += 1
| if $i <= 50 then .radicals[$i] = prod(.factors[]) else . end ;
if $i == 50
then "The radicals for the first 50 positive integers are:",
(.radicals[1:] | _nwise(10) | map(lpad(4)) | join(" ")),
""
elif $i | IN( 99999, 499999, 999999)
then "Radical for \($i|lpad(8)): \(prod(.factors[])|lpad(8))"
elif $i == 1e6
then "\nBreakdown of numbers of distinct prime factors",
"for positive integers from 1 to 1,000,000:",
(range(1; 8) as $i
| " \($i): \(.counts[$i]|lpad(8))"),
" ---------",
" \(sum(.counts[]))"
else empty
end);
def task2:
def pad: lpad(6);
(1000|primeSieve|map(select(.))) as $primes1k
| { pcount: (1e6|primeCount),
ppcount: 0 }
| reduce $primes1k[] as $p (.;
.p2 = $p
| .done = false
| until(.done;
.p2 *= $p
| if .p2 > 1e6 then .done = true
else .ppcount += 1
end ) )
| "\nFor primes or powers (>1) thereof <= 1,000,000:",
" Number of primes = \(.pcount|pad)",
" Number of powers = \(.ppcount|pad)",
" Add 1 for number 1 = \(1|pad)",
" ------",
" \( (.pcount + .ppcount + 1)|pad)" ;
task1, task2
The radicals for the first 50 positive integers are: 1 2 3 2 5 6 7 2 3 10 11 6 13 14 15 2 17 6 19 10 21 22 23 6 5 26 3 14 29 30 31 2 33 34 35 6 37 38 39 10 41 42 43 22 15 46 47 6 7 10 Radical for 99999: 33333 Radical for 499999: 3937 Radical for 999999: 111111 Breakdown of numbers of distinct prime factors for positive integers from 1 to 1,000,000: 1: 78735 2: 288726 3: 379720 4: 208034 5: 42492 6: 2285 7: 8 --------- 1000000 For primes or powers (>1) thereof <= 1,000,000: Number of primes = 78498 Number of powers = 236 Add 1 for number 1 = 1 ------ 78735
Julia
using Formatting, Primes, UnicodePlots
radical(n) = prod(map(first, factor(n).pe))
radicallength(n) = length(factor(n).pe)
println("The radicals for the first 50 positive integers are:")
foreach(p -> print(rpad(p[2], 4), p[1] % 10 == 0 ? "\n" : ""), enumerate(map(radical, 1:50)))
for i in [99999, 499999, 999999]
println("\nRadical for ", format(i, commas=true), ": ", format(radical(i), commas=true))
end
println("\nBreakdown of numbers of distinct prime factors for positive integers from 1 to 1,000,000:")
histogram(map(radicallength, 1:1_000_000), nbins = 8)
println("\nCheck on breakdown:")
primecount = length(primes(1_000_000)) # count of primes to 1 million
powerscount = mapreduce(p -> Int(floor(6 / log10(p)) - 1), +, primes(1000))
println("Prime count to 1 million: ", lpad(primecount, 6))
println("Prime powers less than 1 million: ", lpad(powerscount, 6))
println("Subtotal:", lpad(primecount + powerscount, 32))
println("The integer 1 has 0 prime factors: ", lpad(1, 6))
println("-"^41, "\n", "Overall total:", lpad(primecount + powerscount + 1, 27))
- Output:
The radicals for the first 50 positive integers are: 1 2 3 2 5 6 7 2 3 10 11 6 13 14 15 2 17 6 19 10 21 22 23 6 5 26 3 14 29 30 31 2 33 34 35 6 37 38 39 10 41 42 43 22 15 46 47 6 7 10 Radical for 99,999: 33,333 Radical for 499,999: 3,937 Radical for 999,999: 111,111 Breakdown of numbers of distinct prime factors for positive integers from 1 to 1,000,000: ┌ ┐ [0.0, 1.0) ┤▏ 1 [1.0, 2.0) ┤██████▌ 78 734 [2.0, 3.0) ┤███████████████████████▌ 288 726 [3.0, 4.0) ┤███████████████████████████████ 379 720 [4.0, 5.0) ┤████████████████▉ 208 034 [5.0, 6.0) ┤███▌ 42 492 [6.0, 7.0) ┤▎ 2 285 [7.0, 8.0) ┤▏ 8 └ ┘ Frequency Check on breakdown: Prime count to 1 million: 78498 Prime powers less than 1 million: 236 Subtotal: 78734 The integer 1 has 0 prime factors: 1 ----------------------------------------- Overall total: 78735
MAD
NORMAL MODE IS INTEGER
INTERNAL FUNCTION(A,B)
ENTRY TO REM.
FUNCTION RETURN A-A/B*B
END OF FUNCTION
INTERNAL FUNCTION(NN)
ENTRY TO RADIC.
KN = NN
DPF = 0
RAD = 1
WHENEVER KN.E.0, FUNCTION RETURN 0
WHENEVER REM.(KN,2).E.0
DPF = 1
RAD = 2
THROUGH DIV2, FOR KN=KN, 0, REM.(KN,2).NE.0
DIV2 KN = KN / 2
END OF CONDITIONAL
THROUGH ODD, FOR FAC=3, 2, FAC.G.KN
WHENEVER REM.(KN,FAC).E.0
DPF = DPF + 1
RAD = RAD * FAC
THROUGH DIVP, FOR KN=KN, 0, REM.(KN,FAC).NE.0
DIVP KN = KN / FAC
END OF CONDITIONAL
ODD CONTINUE
FUNCTION RETURN RAD
END OF FUNCTION
R PRINT RADICALS FOR 1..50
VECTOR VALUES RADLIN = $10(I5)*$
PRINT COMMENT $ RADICALS OF 1 TO 50$
THROUGH RADL, FOR L=0, 10, L.GE.50
RADL PRINT FORMAT RADLIN,
0 RADIC.(L+1),RADIC.(L+2),RADIC.(L+3),RADIC.(L+4),
1 RADIC.(L+5),RADIC.(L+6),RADIC.(L+7),RADIC.(L+8),
2 RADIC.(L+9),RADIC.(L+10)
R PRINT RADICALS OF TASK NUMBERS
PRINT COMMENT $ $
VECTOR VALUES RADNUM = $14HTHE RADICAL OF,I7,S1,2HIS,I7*$
THROUGH RADN, FOR VALUES OF N = 99999, 499999, 999999
RADN PRINT FORMAT RADNUM,N,RADIC.(N)
R FIND DISTRIBUTION
PRINT COMMENT $ $
DIMENSION DIST(8)
THROUGH ZERO, FOR D = 0, 1, D.G.7
ZERO DIST(D) = 0
THROUGH CNTDST, FOR N = 1, 1, N.G.1000000
RADIC.(N)
CNTDST DIST(DPF) = DIST(DPF) + 1
PRINT COMMENT $ DISTRIBUTION OF RADICALS$
VECTOR VALUES DISTLN = $I1,2H: ,I8*$
THROUGH SHWDST, FOR D = 0, 1, D.G.7
SHWDST PRINT FORMAT DISTLN,D,DIST(D)
END OF PROGRAM
- Output:
RADICALS OF 1 TO 50 1 2 3 2 5 6 7 2 3 10 11 6 13 14 15 2 17 6 19 10 21 22 23 6 5 26 3 14 29 30 31 2 33 34 35 6 37 38 39 10 41 42 43 22 15 46 47 6 7 10 THE RADICAL OF 99999 IS 33333 THE RADICAL OF 499999 IS 3937 THE RADICAL OF 999999 IS 111111 DISTRIBUTION OF RADICALS 0: 1 1: 78734 2: 288726 3: 379720 4: 208034 5: 42492 6: 2285 7: 8
Nim
import std/[math, strformat, strutils]
const N = 1_000_000
### Build list of primes.
func isPrime(n: Natural): bool =
## Return true if "n" is prime.
## "n" should not be a mutiple of 2 or 3.
var k = 5
var delta = 2
while k * k <= n:
if n mod k == 0: return false
inc k, delta
delta = 6 - delta
result = true
var primes = @[2, 3]
var n = 5
var step = 2
while n <= N:
if n.isPrime:
primes.add n
inc n, step
step = 6 - step
### Build list of distinct prime factors to
### compute radical and distinct factor count.
var primeFactors: array[1..N, seq[int]]
for p in primes:
for n in countup(p, N, p):
primeFactors[n].add p
template radical(n: int): int = prod(primeFactors[n])
template factorCount(n: int): int = primeFactors[n].len
### Task ###
echo "Radical of first 50 positive integers:"
for n in 1..50:
stdout.write &"{radical(n):2}"
stdout.write if n mod 10 == 0: '\n' else: ' '
echo()
for n in [99_999, 499_999, 999_999]:
echo &"Radical for {insertSep($n):>7}: {insertSep($radical(n)):>7}"
echo()
echo "Distribution of the first one million positive"
echo "integers by numbers of distinct prime factors:"
var counts: array[0..7, int]
for n in 1..1_000_000:
inc counts[factorCount(n)]
for n, count in counts:
echo &"{n}: {insertSep($count):>7}"
echo()
### Bonus ###
echo "Number of primes and powers of primes"
echo "less than or equal to one million:"
var count = 0
const LogN = ln(N.toFloat)
for p in primes:
inc count, int(LogN / ln(p.toFloat))
echo insertSep($count)
- Output:
Radical of first 50 positive integers: 1 2 3 2 5 6 7 2 3 10 11 6 13 14 15 2 17 6 19 10 21 22 23 6 5 26 3 14 29 30 31 2 33 34 35 6 37 38 39 10 41 42 43 22 15 46 47 6 7 10 Radical for 99_999: 33_333 Radical for 499_999: 3_937 Radical for 999_999: 111_111 Distribution of the first one million positive integers by numbers of distinct prime factors: 0: 1 1: 78_734 2: 288_726 3: 379_720 4: 208_034 5: 42_492 6: 2_285 7: 8 Number of primes and powers of primes less than or equal to one million: 78_734
Pascal
Free Pascal
program Radical;
{$IFDEF FPC} {$MODE DELPHI}{$Optimization ON,ALL} {$ENDIF}
{$IFDEF WINDOWS}{$APPTYPE CONSOLE}{$ENDIF}
//much faster would be
//https://rosettacode.org/wiki/Factors_of_an_integer#using_Prime_decomposition
const
LIMIT = 1000*1000;
DeltaMod235 : array[0..7] of Uint32 = (4, 2, 4, 2, 4, 6, 2, 6);
type
tRadical = record
number,radical,PrFacCnt: Uint64;
isPrime : boolean;
end;
function GetRadical(n: UInt32):tRadical;forward;
function CommaUint(n : Uint64):AnsiString;
//commatize only positive Integers
var
fromIdx,toIdx :Int32;
pRes : pChar;
Begin
str(n,result);
fromIdx := length(result);
toIdx := fromIdx-1;
if toIdx < 3 then
exit;
toIdx := 4*(toIdx DIV 3)+toIdx MOD 3 +1 ;
setlength(result,toIdx);
pRes := @result[1];
dec(pRes);
repeat
pRes[toIdx] := pRes[FromIdx];
pRes[toIdx-1] := pRes[FromIdx-1];
pRes[toIdx-2] := pRes[FromIdx-2];
pRes[toIdx-3] := ',';
dec(toIdx,4);
dec(FromIdx,3);
until FromIdx<=3;
while fromIdx>=1 do
Begin
pRes[toIdx] := pRes[FromIdx];
dec(toIdx);
dec(fromIdx);
end;
end;
procedure OutRadical(n: Uint32);
Begin
writeln('Radical for ',CommaUint(n):8,':',CommaUint(GetRadical(n).radical):8);
end;
function GetRadical(n: UInt32):tRadical;
var
q,divisor, rest: UInt32;
nxt : Uint32;
begin
with result do
Begin
number := n;
radical := n;
PrFacCnt := 1;
isPrime := false;
end;
if n <= 1 then
EXIT;
if n in [2,3,5,7,11,13,17,19,23,29,31] then
Begin
with result do
Begin
isprime := true;
PrFacCnt := 1;
end;
EXIT;
end;
with result do
Begin
radical := 1;
PrFacCnt := 0;
end;
rest := n;
if rest AND 1 = 0 then
begin
with result do begin radical := 2; PrFacCnt:= 1;end;
repeat
rest := rest shr 1;
until rest AND 1 <> 0;
end;
if rest < 3 then
EXIT;
q := rest DIV 3;
if rest-q*3= 0 then
begin
with result do begin radical *= 3; inc(PrFacCnt);end;
repeat
rest := q;
q := rest DIV 3;
until rest-q*3 <> 0;
end;
if rest < 5 then
EXIT;
q := rest DIV 5;
if rest-q*5= 0 then
begin
with result do begin radical *= 5;inc(PrFacCnt);end;
repeat
rest := q;
q := rest DIV 5;
until rest-q*5 <> 0;
end;
divisor := 7;
nxt := 0;
repeat;
if rest < sqr(divisor) then
BREAK;
q := rest DIV divisor;
if rest-q*divisor= 0 then
begin
with result do begin radical *= divisor; inc(PrFacCnt);end;
repeat
rest := q;
q := rest DIV divisor;
until rest-q*divisor <> 0;
end;
divisor += DeltaMod235[nxt];
nxt := (nxt+1) AND 7;
until false;
//prime ?
if rest = n then
with result do begin radical := n;PrFacCnt:=1;isPrime := true; end
else
if rest >1 then
with result do begin radical *= rest;inc(PrFacCnt);end;
end;
var
Rad:tRadical;
CntOfPrFac : array[0..9] of Uint32;
j,sum,countOfPrimes,CountOfPrimePowers: integer;
begin
writeln('The radicals for the first 50 positive integers are:');
for j := 1 to 50 do
Begin
write (GetRadical(j).radical:4);
if j mod 10 = 0 then
Writeln;
end;
writeln;
OutRadical( 99999);
OutRadical(499999);
OutRadical(999999);
writeln;
writeln('Breakdown of numbers of distinct prime factors');
writeln('for positive integers from 1 to ',CommaUint(LIMIT));
countOfPrimes:=0;
CountOfPrimePowers :=0;
For j := Low(CntOfPrFac) to High(CntOfPrFac) do
CntOfPrFac[j] := 0;
For j := 1 to LIMIT do
Begin
Rad := GetRadical(j);
with rad do
Begin
IF isPrime then
inc(countOfPrimes)
else
if (j>1)AND(PrFacCnt= 1) then
inc(CountOfPrimePowers);
end;
inc(CntOfPrFac[Rad.PrFacCnt]);
end;
sum := 0;
For j := Low(CntOfPrFac) to High(CntOfPrFac) do
if CntOfPrFac[j] > 0 then
Begin
writeln(j:3,': ',CommaUint(CntOfPrFac[j]):10);
inc(sum,CntOfPrFac[j]);
end;
writeln('sum: ',CommaUint(sum):10);
writeln;
sum := countOfPrimes+CountOfPrimePowers+1;
writeln('For primes or powers (>1) there of <= ',CommaUint(LIMIT));
Writeln(' Number of primes =',CommaUint(countOfPrimes):8);
Writeln(' Number of prime powers =',CommaUint(CountOfPrimePowers):8);
Writeln(' Add 1 for number = 1');
Writeln(' sums to =',CommaUint(sum):8);
{$IFDEF WINDOWS}readln;{$ENDIF}
end.
- @TIO.RUN:
The radicals for the first 50 positive integers are: 1 2 3 2 5 6 7 2 3 10 11 6 13 14 15 2 17 6 19 10 21 22 23 6 5 26 3 14 29 30 31 2 33 34 35 6 37 38 39 10 41 42 43 22 15 46 47 6 7 10 Radical for 99,999: 33,333 Radical for 499,999: 3,937 Radical for 999,999: 111,111 Breakdown of numbers of distinct prime factors for positive integers from 1 to 1,000,000 1: 78,735 2: 288,726 3: 379,720 4: 208,034 5: 42,492 6: 2,285 7: 8 sum: 1,000,000 For primes or powers (>1) there of <= 1,000,000 Number of primes = 78,498 Number of prime powers = 236 Add 1 for number = 1 sums to = 78,735 Real time: 0.310 s User time: 0.285 s Sys. time: 0.022 s CPU share: 99.16 %
alternative
Using modified factors of integer inserted radical.
program Radical_2;
// gets factors of consecutive integers fast limited to 1.2e11
{$IFDEF FPC}{$MODE DELPHI}{$OPTIMIZATION ON,ALL}{$ENDIF}
{$IFDEF Windows}{$APPTYPE CONSOLE}{$ENDIF}
uses
sysutils
{$IFDEF WINDOWS},Windows{$ENDIF}
;
//######################################################################
//prime decomposition
const
//HCN(86) > 1.2E11 = 128,501,493,120 count of divs = 4096 7 3 1 1 1 1 1 1 1
HCN_DivCnt = 4096;
type
tItem = Uint64;
tDivisors = array [0..HCN_DivCnt] of tItem;
tpDivisor = pUint64;
const
//used odd size for test only
SizePrDeFe = 32768;//*+64 <= 64kb level I or 2 Mb ~ level 2 cache
type
tdigits = array [0..31] of Uint32;
//the first number with 11 different prime factors =
//2*3*5*7*11*13*17*19*23*29*31 = 2E11
//64 byte
tprimeFac = packed record
pfSumOfDivs,
pfRemain,
pfRadical : Uint64;
pfDivCnt,
pfPrimeCnt : Uint32;
pfpotPrimIdx : array[0..9] of word;
pfpotMax : array[0..11] of byte;
end;
tpPrimeFac = ^tprimeFac;
tPrimeDecompField = array[0..SizePrDeFe-1] of tprimeFac;
tPrimes = array[0..65535] of Uint32;
var
{$ALIGN 8}
SmallPrimes: tPrimes;
{$ALIGN 32}
PrimeDecompField :tPrimeDecompField;
pdfIDX,pdfOfs: NativeInt;
procedure InitSmallPrimes;
//get primes. #0..65535.Sieving only odd numbers
const
MAXLIMIT = (821641-1) shr 1;
var
pr : array[0..MAXLIMIT] of byte;
p,j,d,flipflop :NativeUInt;
Begin
SmallPrimes[0] := 2;
fillchar(pr[0],SizeOf(pr),#0);
p := 0;
repeat
repeat
p +=1
until pr[p]= 0;
j := (p+1)*p*2;
if j>MAXLIMIT then
BREAK;
d := 2*p+1;
repeat
pr[j] := 1;
j += d;
until j>MAXLIMIT;
until false;
SmallPrimes[1] := 3;
SmallPrimes[2] := 5;
j := 3;
d := 7;
flipflop := (2+1)-1;//7+2*2,11+2*1,13,17,19,23
p := 3;
repeat
if pr[p] = 0 then
begin
SmallPrimes[j] := d;
inc(j);
end;
d += 2*flipflop;
p+=flipflop;
flipflop := 3-flipflop;
until (p > MAXLIMIT) OR (j>High(SmallPrimes));
end;
function OutPots(pD:tpPrimeFac;n:NativeInt):Ansistring;
var
s: String[31];
chk,p,i: NativeInt;
Begin
str(n,s);
result := s+' :';
with pd^ do
begin
str(pfDivCnt:3,s);
result += s+' : ';
chk := 1;
For n := 0 to pfPrimeCnt-1 do
Begin
if n>0 then
result += '*';
p := SmallPrimes[pfpotPrimIdx[n]];
chk *= p;
str(p,s);
result += s;
i := pfpotMax[n];
if i >1 then
Begin
str(pfpotMax[n],s);
result += '^'+s;
repeat
chk *= p;
dec(i);
until i <= 1;
end;
end;
p := pfRemain;
If p >1 then
Begin
str(p,s);
chk *= p;
result += '*'+s;
end;
str(chk,s);
result += '_chk_'+s+'<';
str(pfSumOfDivs,s);
result += '_SoD_'+s+'<';
end;
end;
function smplPrimeDecomp(n:Uint64):tprimeFac;
var
pr,i,pot,fac,q :NativeUInt;
Begin
with result do
Begin
pfDivCnt := 1;
pfSumOfDivs := 1;
pfRemain := n;
pfRadical := 1;
pfPrimeCnt := 0;
pfpotPrimIdx[0] := 1;
pfpotMax[0] := 0;
i := 0;
while i < High(SmallPrimes) do
begin
pr := SmallPrimes[i];
q := n DIV pr;
//if n < pr*pr
if pr > q then
BREAK;
if n = pr*q then
Begin
pfpotPrimIdx[pfPrimeCnt] := i;
pot := 0;
fac := pr;
pfRadical *= pr;
repeat
n := q;
q := n div pr;
pot+=1;
fac *= pr;
until n <> pr*q;
pfpotMax[pfPrimeCnt] := pot;
pfDivCnt *= pot+1;
pfSumOfDivs *= (fac-1)DIV(pr-1);
inc(pfPrimeCnt);
end;
inc(i);
end;
pfRemain := n;
if n > 1 then
Begin
pfRadical *= pfRemain;
pfDivCnt *= 2;
pfSumOfDivs *= n+1
end;
end;
end;
function CnvtoBASE(var dgt:tDigits;n:Uint64;base:NativeUint):NativeInt;
//n must be multiple of base aka n mod base must be 0
var
q,r: Uint64;
i : NativeInt;
Begin
fillchar(dgt,SizeOf(dgt),#0);
i := 0;
n := n div base;
result := 0;
repeat
r := n;
q := n div base;
r -= q*base;
n := q;
dgt[i] := r;
inc(i);
until (q = 0);
//searching lowest pot in base
result := 0;
while (result<i) AND (dgt[result] = 0) do
inc(result);
inc(result);
end;
function IncByBaseInBase(var dgt:tDigits;base:NativeInt):NativeInt;
var
q :NativeInt;
Begin
result := 0;
q := dgt[result]+1;
if q = base then
repeat
dgt[result] := 0;
inc(result);
q := dgt[result]+1;
until q <> base;
dgt[result] := q;
result +=1;
end;
function SieveOneSieve(var pdf:tPrimeDecompField):boolean;
var
dgt:tDigits;
i,j,k,pr,fac,n,MaxP : Uint64;
begin
n := pdfOfs;
if n+SizePrDeFe >= sqr(SmallPrimes[High(SmallPrimes)]) then
EXIT(FALSE);
//init
for i := 0 to SizePrDeFe-1 do
begin
with pdf[i] do
Begin
pfDivCnt := 1;
pfSumOfDivs := 1;
pfRadical := 1;
pfRemain := n+i;
pfPrimeCnt := 0;
pfpotPrimIdx[0] := 0;
pfpotMax[0] := 0;
end;
end;
//first factor 2. Make n+i even
i := (pdfIdx+n) AND 1;
IF (n = 0) AND (pdfIdx<2) then
i := 2;
repeat
with pdf[i] do
begin
j := BsfQWord(n+i);
pfPrimeCnt := 1;
pfRadical := 2;
pfpotPrimIdx[0] := 0;
pfpotMax[0] := j;
pfRemain := (n+i) shr j;
pfSumOfDivs := (Uint64(1) shl (j+1))-1;
pfDivCnt := j+1;
end;
i += 2;
until i >=SizePrDeFe;
//i now index in SmallPrimes
i := 0;
maxP := trunc(sqrt(n+SizePrDeFe))+1;
repeat
//search next prime that is in bounds of sieve
if n = 0 then
begin
repeat
inc(i);
pr := SmallPrimes[i];
k := pr-n MOD pr;
if k < SizePrDeFe then
break;
until pr > MaxP;
end
else
begin
repeat
inc(i);
pr := SmallPrimes[i];
k := pr-n MOD pr;
if (k = pr) AND (n>0) then
k:= 0;
if k < SizePrDeFe then
break;
until pr > MaxP;
end;
//no need to use higher primes
if pr*pr > n+SizePrDeFe then
BREAK;
//j is power of prime
j := CnvtoBASE(dgt,n+k,pr);
repeat
with pdf[k] do
Begin
pfpotPrimIdx[pfPrimeCnt] := i;
pfpotMax[pfPrimeCnt] := j;
pfDivCnt *= j+1;
fac := pr;
pfRadical *= pr;
repeat
pfRemain := pfRemain DIV pr;
dec(j);
fac *= pr;
until j<= 0;
pfSumOfDivs *= (fac-1)DIV(pr-1);
inc(pfPrimeCnt);
k += pr;
j := IncByBaseInBase(dgt,pr);
end;
until k >= SizePrDeFe;
until false;
//correct sum of & count of divisors
for i := 0 to High(pdf) do
Begin
with pdf[i] do
begin
j := pfRemain;
if j <> 1 then
begin
pfRadical *= j;
pfSumOFDivs *= (j+1);
pfDivCnt *=2;
end;
end;
end;
result := true;
end;
function NextSieve:boolean;
begin
dec(pdfIDX,SizePrDeFe);
inc(pdfOfs,SizePrDeFe);
result := SieveOneSieve(PrimeDecompField);
end;
function GetNextPrimeDecomp:tpPrimeFac;
begin
if pdfIDX >= SizePrDeFe then
if Not(NextSieve) then
EXIT(NIL);
result := @PrimeDecompField[pdfIDX];
inc(pdfIDX);
end;
function Init_Sieve(n:NativeUint):boolean;
//Init Sieve pdfIdx,pdfOfs are Global
begin
pdfIdx := n MOD SizePrDeFe;
pdfOfs := n-pdfIdx;
result := SieveOneSieve(PrimeDecompField);
end;
procedure InsertSort(pDiv:tpDivisor; Left, Right : NativeInt );
var
I, J: NativeInt;
Pivot : tItem;
begin
for i:= 1 + Left to Right do
begin
Pivot:= pDiv[i];
j:= i - 1;
while (j >= Left) and (pDiv[j] > Pivot) do
begin
pDiv[j+1]:=pDiv[j];
Dec(j);
end;
pDiv[j+1]:= pivot;
end;
end;
procedure GetDivisors(pD:tpPrimeFac;var Divs:tDivisors);
var
pDivs : tpDivisor;
pPot : UInt64;
i,len,j,l,p,k: Int32;
Begin
pDivs := @Divs[0];
pDivs[0] := 1;
len := 1;
l := 1;
with pD^ do
Begin
For i := 0 to pfPrimeCnt-1 do
begin
//Multiply every divisor before with the new primefactors
//and append them to the list
k := pfpotMax[i];
p := SmallPrimes[pfpotPrimIdx[i]];
pPot :=1;
repeat
pPot *= p;
For j := 0 to len-1 do
Begin
pDivs[l]:= pPot*pDivs[j];
inc(l);
end;
dec(k);
until k<=0;
len := l;
end;
p := pfRemain;
If p >1 then
begin
For j := 0 to len-1 do
Begin
pDivs[l]:= p*pDivs[j];
inc(l);
end;
len := l;
end;
end;
//Sort. Insertsort much faster than QuickSort in this special case
InsertSort(pDivs,0,len-1);
//end marker
pDivs[len] :=0;
end;
procedure AllFacsOut(var Divs:tdivisors;proper:boolean=true);
var
k,j: Int32;
Begin
k := 0;
j := 1;
if Proper then
j:= 2;
repeat
IF Divs[j] = 0 then
BREAK;
write(Divs[k],',');
inc(j);
inc(k);
until false;
writeln(Divs[k]);
end;
const
//LIMIT =2*3*5*7*11*13*17*19*23;
LIMIT =1000*1000;
var
pPrimeDecomp :tpPrimeFac;
Mypd :tPrimeFac;
//Divs:tDivisors;
CntOfPrFac : array[0..9] of Uint32;
T0:Int64;
n : NativeUInt;
Begin
InitSmallPrimes;
T0 := GetTickCount64;
n := 0;
Init_Sieve(0);
pPrimeDecomp := @Mypd;
repeat
// Mypd := smplPrimeDecomp(n);
pPrimeDecomp:= GetNextPrimeDecomp;
if pPrimeDecomp^.pfRemain <> 1 then
inc(CntOfPrFac[pPrimeDecomp^.pfPrimeCnt+1])
else
inc(CntOfPrFac[pPrimeDecomp^.pfPrimeCnt]);
inc(n);
until n > Limit;
T0 := GetTickCount64-T0;
writeln(' Limit = ',OutPots(pPrimeDecomp,LIMIT));
writeln(' runtime ',T0/1000:0:3,' s');
For n := Low(CntOfPrFac) to High(CntOfPrFac) do
writeln(n:2,' : ',CntOfPrFac[n]:8);
end.
- @TIO.RUN fpc -O3 -XX:
Limit = 1000000 : 49 : 2^6*5^6_chk_1000000<_SoD_2480437< runtime 0.058 s //@home runtime 0.017 s 0 : 1 1 : 78735 2 : 288726 3 : 379720 4 : 208034 5 : 42492 6 : 2285 7 : 8 8 : 0 9 : 0 Real time: 0.183 s User time: 0.155 s Sys. time: 0.026 s CPU share: 99.09 % Limit = 223092870 :512 : 2*3*5*7*11*13*17*19*23_chk_223092870<_SoD_836075520< runtime 15.066 s//@home runtime 4.141 s //vs runtime 101.005 s =smplPrimeDecomp 0 : 1 1 : 12285486 2 : 48959467 3 : 76410058 4 : 58585602 5 : 22577473 6 : 4008166 7 : 262905 8 : 3712 9 : 1 Real time: 15.218 s User time: 15.068 s Sys. time: 0.033 s CPU share: 99.23 %
Phix
with javascript_semantics sequence radicals = reinstate(repeat(0,50),1,1), counts = reinstate(repeat(0,8),1,1) for i=2 to 1e6 do sequence f = vslice(prime_powers(i),1) counts[length(f)] += 1 if i<=50 then radicals[i] = product(f) end if if i=50 then printf(1,"The radicals for the first 50 positive integers are:\n%s\n", {join_by(radicals,1,10," ",fmt:="%3d")}) elsif i=99999 or i=499999 or i=999999 then printf(1,"Radical for %,7d: %,7d\n", {i, product(f)}) elsif i=1e6 then printf(1,"\nBreakdown of numbers of distinct prime factors\n") printf(1,"for positive integers from 1 to 1,000,000:\n") for c=1 to 7 do printf(1," %d: %,8d\n", {c, counts[c]}) end for printf(1," ---------\n") printf(1," %,8d\n\n", sum(counts)) end if end for integer pcount = length(get_primes_le(1e6)), ppcount = 0 for p in get_primes_le(1000) do atom p2 = p while true do p2 *= p if p2>1e6 then exit end if ppcount += 1 end while end for printf(1,"For primes or powers (>1) thereof <= 1,000,000:\n") printf(1," Number of primes = %,6d\n", pcount) printf(1," Number of powers = %,6d\n", ppcount) printf(1," Add 1 for number 1 = %,6d\n", 1) printf(1," ------\n") printf(1," %,6d\n", pcount + ppcount + 1)
Output matches other entries, but w/o a charbarchart - should you pine see here, here, here, here, or here.
Raku
use Prime::Factor;
use List::Divvy;
use Lingua::EN::Numbers;
sub radical ($_) { [×] unique .&prime-factors }
say "First fifty radicals:\n" ~
(1..50).map({.&radical}).batch(10)».fmt("%2d").join: "\n";
say '';
printf "Radical for %7s => %7s\n", .&comma, comma .&radical
for 99999, 499999, 999999;
my %rad = 1 => 1;
my $limit = 1e6.Int;
%rad.push: $_ for (2..$limit).race(:1000batch).map: {(unique .&prime-factors).elems => $_};
say "\nRadical factor count breakdown, 1 through {comma $limit}:";
say .key ~ " => {comma +.value}" for sort %rad;
my @primes = (2..$limit).grep: &is-prime;
my int $powers;
@primes.&upto($limit.sqrt.floor).map: -> $p {
for (2..*) { ($p ** $_) < $limit ?? ++$powers !! last }
}
say qq:to/RADICAL/;
Up to {comma $limit}:
Primes: {comma +@primes}
Powers: $powers
Plus 1: 1
Total: {comma 1 + $powers + @primes}
RADICAL
- Output:
First fifty radicals: 1 2 3 2 5 6 7 2 3 10 11 6 13 14 15 2 17 6 19 10 21 22 23 6 5 26 3 14 29 30 31 2 33 34 35 6 37 38 39 10 41 42 43 22 15 46 47 6 7 10 Radical for 99,999 => 33,333 Radical for 499,999 => 3,937 Radical for 999,999 => 111,111 Radical factor count breakdown, 1 through 1,000,000: 1 => 78,735 2 => 288,726 3 => 379,720 4 => 208,034 5 => 42,492 6 => 2,285 7 => 8 Up to 1,000,000: Primes: 78,498 Powers: 236 Plus 1: 1 Total: 78,735
RPL
PDIV
is defined at Prime decomposition
NODUP
is defined at Remove duplicate elements
Standard version
≪ PDIV NODUP 1 1 3 PICK SIZE FOR j OVER j GET * NEXT SWAP DROP ≫ 'RADIX' STO
HP-48G and later models
≪ PDIV NODUP ΠLIST ≫ 'RADIX' STO
Calls to solve the task:
≪ { 1 } 2 50 FOR n n RADIX + NEXT ≫ EVAL 99999 RADIX 499999 RADIX 999999 RADIX ≪ { 7 } 0 CON 1 1 PUT 2 10000 FOR n n PDIV NODUP SIZE DUP2 GET 1 + PUT NEXT ≫ EVAL
Looping one million times would need days to run on HP calculators and would wake up emulator's watchdog timer.
- Output:
5: { 1 2 3 2 5 6 7 2 3 10 11 6 13 14 15 2 17 6 19 10 21 22 23 6 5 26 3 14 29 30 31 2 33 34 35 6 37 38 39 10 41 42 43 22 15 46 47 6 7 10 } 4: 33333 3: 3937 2: 111111 1: { 1281 4097 3695 894 33 0 0 }
Ruby
Adding 3 methods to Integers, but not globally:
module Radical
refine Integer do
require 'prime'
def radical = self == 1 ? 1 : prime_division.map(&:first).inject(&:*)
def num_uniq_prime_factors = prime_division.size
def prime_pow? = prime_division.size == 1
end
end
using Radical
n = 50 # task 1
puts "The radicals for the first #{n} positive integers are:"
(1..n).map(&:radical).each_slice(10){|s| puts "%4d"*s.size % s}
puts # task 2
[99999, 499999 , 999999].each{|n| puts "Radical for %6d: %6d" % [n, n.radical]}
n = 1_000_000 # task 3 & bonus
puts "\nNumbers of distinct prime factors for integers from 1 to #{n}"
(1..n).map(&:num_uniq_prime_factors).tally.each{|kv| puts "%d: %8d" % kv }
puts "\nNumber of primes and powers of primes less than or equal to #{n}: #{(1..n).count(&:prime_pow?)}"
- Output:
The radicals for the first 50 positive integers are: 1 2 3 2 5 6 7 2 3 10 11 6 13 14 15 2 17 6 19 10 21 22 23 6 5 26 3 14 29 30 31 2 33 34 35 6 37 38 39 10 41 42 43 22 15 46 47 6 7 10 Radical for 99999: 33333 Radical for 499999: 3937 Radical for 999999: 111111 Numbers of distinct prime factors for integers from 1 to 1000000 0: 1 1: 78734 2: 288726 3: 379720 4: 208034 5: 42492 6: 2285 7: 8 Number of primes and powers of primes less than or equal to 1000000: 78734
Wren
import "./math" for Int, Nums
import "./seq" for Lst
import "./fmt" for Fmt
var radicals = List.filled(51, 0)
radicals[1] = 1
var counts = List.filled(8, 0)
counts[1] = 1
for (i in 2..1e6) {
var factors = Lst.prune(Int.primeFactors(i))
var fc = factors.count
counts[fc] = counts[fc] + 1
if (i <= 50) radicals[i] = Nums.prod(factors)
if (i == 50) {
System.print("The radicals for the first 50 positive integers are:")
Fmt.tprint("$2d ", radicals.skip(1), 10)
System.print()
} else if (i == 99999 || i == 499999 || i == 999999) {
Fmt.print("Radical for $,7d: $,7d", i, Nums.prod(factors))
} else if (i == 1e6) {
System.print("\nBreakdown of numbers of distinct prime factors")
System.print("for positive integers from 1 to 1,000,000:")
for (i in 1..7) {
Fmt.print(" $d: $,8d", i, counts[i])
}
Fmt.print(" ---------")
Fmt.print(" $,8d", Nums.sum(counts))
Fmt.print("\nor graphically:")
Nums.barChart("", 50, Nums.toStrings(1..7), counts[1..-1])
}
}
var pcount = Int.primeCount(1e6)
var ppcount = 0
var primes1k = Int.primeSieve(1000)
for (p in primes1k) {
var p2 = p
while (true) {
p2 = p2 * p
if (p2 > 1e6) break
ppcount = ppcount + 1
}
}
Fmt.print("\nFor primes or powers (>1) thereof <= 1,000,000:")
Fmt.print(" Number of primes = $,6d", pcount)
Fmt.print(" Number of powers = $,6d", ppcount)
Fmt.print(" Add 1 for number 1 = $,6d", 1)
Fmt.print(" ------")
Fmt.print(" $,6d", pcount + ppcount + 1)
- Output:
The radicals for the first 50 positive integers are: 1 2 3 2 5 6 7 2 3 10 11 6 13 14 15 2 17 6 19 10 21 22 23 6 5 26 3 14 29 30 31 2 33 34 35 6 37 38 39 10 41 42 43 22 15 46 47 6 7 10 Radical for 99,999: 33,333 Radical for 499,999: 3,937 Radical for 999,999: 111,111 Breakdown of numbers of distinct prime factors for positive integers from 1 to 1,000,000: 1: 78,735 2: 288,726 3: 379,720 4: 208,034 5: 42,492 6: 2,285 7: 8 --------- 1,000,000 or graphically: -------------------------------------------------- 1 ■■■■■■■■ 78735 2 ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■ 288726 3 ■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■ 379720 4 ■■■■■■■■■■■■■■■■■■■■■■ 208034 5 ■■■■ 42492 6 ◧ 2285 7 ◧ 8 -------------------------------------------------- For primes or powers (>1) thereof <= 1,000,000: Number of primes = 78,498 Number of powers = 236 Add 1 for number 1 = 1 ------ 78,735
XPL0
include xpllib; \for Print and IsPrime
proc Radical(N); \Return radical of N
int N, D, D0, P;
[D:= 2; D0:= 0; P:= 1;
while N >= D*D do
[while rem(N/D) = 0 do
[if D # D0 then
[P:= P*D;
D0:= D;
];
N:= N/D;
];
D:= D+1;
];
if D # D0 then P:= P*N;
return P;
];
func DistinctFactors(N); \Return count of distinct factors of N
int N, D, D0, C;
[D:= 2; D0:= 0; C:= 0;
while N >= D*D do
[while rem(N/D) = 0 do
[if D # D0 then
[C:= C+1;
D0:= D;
];
N:= N/D;
];
D:= D+1;
];
if D # D0 and N # 1 then C:= C+1;
return C;
];
int N, C, A(10), PC, PPC, P2, P;
[Print("The radicals for the first 50 positive integers are:\n");
for N:= 1 to 50 do
[Print("%4d", Radical(N));
if rem(N/10) = 0 then CrLf(0);
];
Print("\n");
Print("Radical for %6,d: %6,d\n", 99_999, Radical( 99_999));
Print("Radical for %6,d: %6,d\n", 499_999, Radical(499_999));
Print("Radical for %6,d: %6,d\n", 999_999, Radical(999_999));
for N:= 0 to 9 do A(N):= 0;
for N:= 1 to 1_000_000 do
[C:= DistinctFactors(N);
A(C):= A(C)+1;
];
Print("\nBreakdown of numbers of distinct prime factors
for positive integers from 1 to 1,000,000:\n");
C:= 0;
for N:= 0 to 9 do
[if A(N) > 0 then
Print(" %d: %6,d\n", N, A(N));
C:= C + A(N);
];
Print(" ---------\n %,d\n", C);
\Bonus (algorithm from Wren):
PC:= 0;
for N:= 1 to 1_000_000 do
if IsPrime(N) then PC:= PC+1;
Print("\nNumber of primes: %5,d\n", PC);
PPC:= 0;
for P:= 1 to sqrt(1_000_000) do
[if IsPrime(P) then
[P2:= P;
loop [P2:= P2 * P;
if P2 > 1_000_000 then quit;
PPC:= PPC+1;
];
];
];
Print("Number of powers: %5,d\n", PPC);
if IsPrime(N) then PC:= PC+1;
Print("Total : %5,d\n", PC+PPC);
]
- Output:
The radicals for the first 50 positive integers are: 1 2 3 2 5 6 7 2 3 10 11 6 13 14 15 2 17 6 19 10 21 22 23 6 5 26 3 14 29 30 31 2 33 34 35 6 37 38 39 10 41 42 43 22 15 46 47 6 7 10 Radical for 99,999: 33,333 Radical for 499,999: 3,937 Radical for 999,999: 111,111 Breakdown of numbers of distinct prime factors for positive integers from 1 to 1,000,000: 0: 1 1: 78,734 2: 288,726 3: 379,720 4: 208,034 5: 42,492 6: 2,285 7: 8 --------- 1,000,000 Number of primes: 78,498 Number of powers: 236 Total : 78,734