use strict; use warnings; my @primes = ( 2, 3 ); my $candidate = $primes[-1] + 2; my $max_prime = shift || 100_000; CANDIDATE: while ( $candidate < $max_prime ) { my $sqrt_candidate = sqrt $candidate; PRIME: foreach my $prime ( @primes ) { last PRIME if $prime > $sqrt_candidate; next CANDIDATE if 0 == $candidate % $prime; } push @primes, $candidate; } continue { $candidate += 2; } print join q{,}, @primes; print "\n";