Math? Primes will only appear in columns whose index is coprime with 12. That's because 12n+2 is divisible by 2. 12n+3 by 3, etc for 12n+4, 12n+6, 12n+8, 12n+9

Math? Primes will only appear in columns whose index is coprime with 12. That's because 12n+2 is divisible by 2. 12n+3 by 3, etc for 12n+4, 12n+6, 12n+8, 12n+9, 12n+10. (For n>0. that's why there are primes on the first line)