Pairs of primes separated by a single number are called prime pairs. Examples are 17 and 19. Prove that the number between a prime pair is always divisible by 6 (assuming both numbers in the pair are greater than 6).

(From http://www.ocf.berkeley.edu/~wwu/riddles/intro.shtml )

(In reply to Stronger result by Steve Herman)

5 and 7 are not both greater than 3!=6. What is your point here?

Posted by Richard on 2006-06-08 19:48:38