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- #!/usr/bin/perl
- # Author: Daniel "Trizen" Șuteu
- # License: GPLv3
- # Website: https://github.com/trizen
- # https://projecteuler.net/problem=58
- # Runtime: 0.040s
- use 5.010;
- use strict;
- use ntheory qw(is_prime);
- my $i = 1;
- my $primes = 0;
- while (1) {
- $primes += grep { is_prime($_) } (
- 3 + $i * (4 * $i - 6),
- 5 + $i * (4 * $i - 8),
- 7 + $i * (4 * $i - 10)
- );
- if ($i > 4 and ($primes / (4 * ($i - 1) + 1) < 0.1)) {
- say 2 * ($i - 1) + 1;
- last;
- }
- ++$i;
- }
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