Prime Sieve of Eratosthenes

Pseudo-code
func sieve( integer N ) var is_prime as array of true of size N.    is_prime[1] = false i = 2 while ( i * i <= N ) if ( is_prime[i] ) for j = i * i to N, in steps of i                     is_prime[j] = false i = i + 1 end func
 * Sieves up to N.
 * if is_prime[i] is true, then i is a prime.