eliminate indexes which does not produce primes
for i in range ( 1 , int ( ( nNew - 1 ) / 2 ) + 1 ) : NEW_LINE INDENT for j in range ( ( ( i * ( i + 1 ) ) << 1 ) , ( int ( n / 2 ) + 1 ) , ( 2 * i + 1 ) ) : NEW_LINE INDENT marked [ j ] = 1 ; NEW_LINE DEDENT DEDENT