*In angry Megatron voice*: PRIME!!!

sieve.p6

sub primes-sieve3(Int $max) {
    my int @sieve;
    my int $effective-max = ($max-1) div 2;
    lazy gather for 1 .. $effective-max -> int $i {
        FIRST take 2;
        next if @sieve[$i];
        my int $prime = 2 * $i + 1;
        take $prime;
        my $fill-range = ($effective-max - $i) div $prime;
        for 1 .. $fill-range -> int $j {
            @sieve[$prime * $j + $i] = 1;
        }
    }
}