Find four distinct positive integers such that:
a. Each of them is below 500.
b. Multiplying any two of them and then incrementing the product by 1
produces a square number.

Same answer if the word "distinct" is removed from the problem.  There are no solutions where the integers are not distinct, because a*b + 1 is not square if a = b.

Posted by Steve Herman on 2016-12-04 12:03:45