Stores the product of every pair of prime number
Vector < Integer > prod = new Vector < > ( ) ; SieveOfEratosthenes ( ) ; int l = primes . size ( ) ; for ( int i = 0 ; i < l ; i ++ ) { for ( int j = i + 1 ; j < l ; j ++ ) { if ( primes . get ( i ) * primes . get ( j ) > 0 ) prod . add ( primes . get ( i ) * primes . get ( j ) ) ; } }