N is a positive integer. If you list the positive integers in rows of N such that the first row contains 1 to N, the second row contains N+1 to 2*N, and so on, then the first row with no prime is immediately followed by another row with no prime. What is N?

(In reply to

re: My solution by Math Man)

Re:

"....*When N is large, there will be many gaps containing 1 row before there is a gap containing 2 rows* "

We have only your word for it.

Why do you think so?