Main logic of Sundaram . Mark all numbers which do not generate prime number by doing 2 * i + 1
for i in range ( 1 , ( int ( math . sqrt ( MAX ) ) - 1 ) // 2 + 1 ) : NEW_LINE INDENT j = ( i * ( i + 1 ) ) << 1 NEW_LINE while ( j <= MAX // 2 ) : NEW_LINE INDENT marked [ j ] = True NEW_LINE j = j + 2 * i + 1 NEW_LINE DEDENT DEDENT