Answer:
Frank is wrong
Step-by-step explanation:

35 is a multiply by 5 so it is not a prime number.
All socks together: 13
Black socks: 3
Probability to pick out black socks: 3/13
After one pick out (You picked out a pair of black socks):
Probability to pick out black socks: 2/12
Multiply them:
2/12 * 3/13 = 1/26 ≈ 0,038
A15=243
74-61=13
87-61=13
So they're adding 13 every time.
A15 is 11 terms from A4 which is the last one you are given so 11*13=143
143+100=243
59049/1048576 the / is a fraction