Sexy Prime Generator
// A short prime tester: | |
// t(11) -> true | |
// t(12) -> false | |
function t( | |
n, //Input | |
i //Placeholder | |
){ | |
for(i=2;i<n;i++) | |
if(!(n%i)) | |
return!1; | |
return!0 | |
} | |
// Sexy prime generator | |
// https://en.wikipedia.org/wiki/Sexy_prime | |
function s( | |
n, //Input | |
p //Placeholder | |
){ | |
// Loop through all numbers from 2 till n-6, checking primacy of i and i+6 | |
for( | |
p=[], //Initialize array | |
i=2; | |
i<n-6; | |
i++ | |
) | |
// If both i and i+6 are prime, add to p | |
if(t(i)&&t(i+6)) | |
p.push([i,i+6]); | |
return p | |
} |
DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE | |
Version 2, December 2004 | |
Copyright (C) 2012 Inkbug | |
Everyone is permitted to copy and distribute verbatim or modified | |
copies of this license document, and changing it is allowed as long | |
as the name is changed. | |
DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE | |
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION | |
0. You just DO WHAT THE FUCK YOU WANT TO. |
{ | |
"name": "SexyPrimes", | |
"description": "A Sexy Prime generator, plus a prime checker.", | |
"keywords": [ | |
"prime", | |
"generator" | |
] | |
} |
<!DOCTYPE html> | |
<title>Sexy Primes</title> | |
<div>Expected value: <b>[[5,11],[7,13]]</b></div> | |
<div>Actual value: <b id="ret"></b></div> | |
<script> | |
// write a small example that shows off the API for your example | |
// and tests it in one fell swoop. | |
function t(n,i){for(i=2;i<n;i++)if(!(n%i))return!1;return!0}function s(n,p){for(p=[],i=2;i<n-6;i++)if(t(i)&&t(i+6))p.push([i,i+6]);return p} | |
document.getElementById( "ret" ).innerHTML = s(15) | |
</script> |
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tsaniel commentedAug 3, 2012
Just simply combine two functions:
function f(a,b,c,d,e){for(d=c=[];b?b%--a:d++<a-6;)b||f(d,d)|f(e=d+6,e)||c.push([d,e]);return b?a^1:c}