A prime number is one that is evenly divisible only by 1 or itself. Note that the problem specifies that the output is 0 for primes and is thus 1 for numbers that are not prime. The first nonprime is 4 (2 2). Indeed, all of the even numbers (other than 2) are nonprimes. Because 0 never occurs, the output for the first row is a don’t care.