S is a set of N distinct positive integers such that no member of S has a prime factor greater than 35. Let P be the set of products of members of S taken 2 at a time. (For example, if x, y and z are members of S, then xy, xz and yz will be members of P.)

What is the smallest value of N for which it is certain that P contains a perfect square?

Well done, all.  I concur.

Posted by Steve Herman on 2004-11-15 08:04:54