Duffinian numbers: Difference between revisions

=={{header|ALGOL 68}}==

Constructs a table of divisor counts without doing any divisions.

INT max number := 500 000; # largest number we will consider #

# iterative Greatest Common Divisor routine, returns the gcd of m and n #

FI

OD

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<pre>

=={{header|AppleScript}}==

As is often the case with these tasks, it takes as much code to format the output as it does to get the numbers. :)

if (n < 2) then return 0

set sum to 1

end task

 

 

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4 8 9 16 21 25 27 32 35 36 39 49 50 55 57 63 64 65 75 77

81 85 93 98 100 111 115 119 121 125 128 129 133 143 144 155 161 169 171 175

11663 11664 11665

12481 12482 12483

 

=={{header|Arturo}}==

 

and? [not? prime? n]

[

loop split.every: 5 first15 'row [

print map row 'item -> pad.right as.code item 17

 

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=={{header|C++}}==

#include <iostream>

#include <numeric>

}

std::cout << '\n';

 

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=={{header|Factor}}==

{{works with|Factor|0.99 2021-06-02}}

lists.lazy math math.primes math.primes.factors math.statistics

prettyprint sequences sequences.deep ;

 

"First 15 Duffinian triplets:" print

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<pre>

{{trans|Wren}}

{{libheader|Go-rcu}}

 

import (

fmt.Println(s[1 : len(s)-1])

}

 

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Implementation:

 

composite=: 1&< * 0 = 1&p:

 

Task examples:

 

4 8 9 16 21 25 27 32 35 36

39 49 50 55 57 63 64 65 75 77

6049 6050 6051

6399 6400 6401

 

=={{header|Julia}}==

 

function σ(n)

 

testDuffinians()

<pre>

First 50 Duffinian numbers:

 

=={{header|Mathematica}}/{{header|Wolfram Language}}==

DuffianQ[n_Integer] := CompositeQ[n] \[And] CoprimeQ[DivisorSigma[1, n], n]

dns = Select[DuffianQ][Range[1000000]];

Take[dns, UpTo[50]]

triplets = ToString[dns[[#]]] <> "\[LongDash]" <> ToString[dns[[# + 2]]] & /@ SequencePosition[Differences[dns], {1, 1}][[All, 1]]

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First 50 Duffinian numbers and Duffinian triplets below a million:

=={{header|Perl}}==

{{libheader|ntheory}}

use warnings;

use feature <say state>;

 

say 'First 39 Duffinian triplets:';

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<pre>First 50 Duffinian numbers:

 

=={{header|Phix}}==

<span style="color: #008080;">with</span> <span style="color: #008080;">javascript_semantics</span>

<span style="color: #004080;">sequence</span> <span style="color: #000000;">duffinian</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{</span><span style="color: #004600;">false</span><span style="color: #0000FF;">}</span>

<span style="color: #000000;">p</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">apply</span><span style="color: #0000FF;">(</span><span style="color: #004600;">true</span><span style="color: #0000FF;">,</span><span style="color: #7060A8;">pad_tail</span><span style="color: #0000FF;">,{</span><span style="color: #7060A8;">apply</span><span style="color: #0000FF;">(</span><span style="color: #004600;">true</span><span style="color: #0000FF;">,</span><span style="color: #7060A8;">sprintf</span><span style="color: #0000FF;">,{{</span><span style="color: #008000;">"[%d,%d,%d]"</span><span style="color: #0000FF;">},</span><span style="color: #000000;">s</span><span style="color: #0000FF;">}),</span><span style="color: #000000;">24</span><span style="color: #0000FF;">})</span>

<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"First 50 Duffinian triplets:\n%s\n"</span><span style="color: #0000FF;">,{</span><span style="color: #7060A8;">join_by</span><span style="color: #0000FF;">(</span><span style="color: #000000;">p</span><span style="color: #0000FF;">,</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #000000;">4</span><span style="color: #0000FF;">,</span><span style="color: #008000;">" "</span><span style="color: #0000FF;">)})</span>

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<pre>

 

=={{header|Raku}}==

 

my @duffinians = lazy (3..*).hyper.grep: { !.is-prime && $_ gcd .&divisors.sum == 1 };

put "\nFirst 40 Duffinian triplets:\n" ~

((^∞).grep: -> $n { (@duffinians[$n] + 1 == @duffinians[$n + 1]) && (@duffinians[$n] + 2 == @duffinians[$n + 2]) })[^40]\

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<pre>First 50 Duffinian numbers:

 

=={{header|Sidef}}==

n.is_composite && n.is_coprime(n.sigma)

}

15.by{|n| ^3 -> all {|k| is_duffinian(n+k) } }.each {|n|

printf("(%s, %s, %s)\n", n, n+1, n+2)

 

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{{libheader|Wren-seq}}

{{libheader|Wren-fmt}}

import "./seq" for Lst

import "./fmt" for Fmt

}

System.print("\nFirst 50 Duffinian triplets:")

 

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=={{header|XPL0}}==

int N, I;

[if N <= 2 then return N = 2;

N:= N+1;

];

 

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