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.

(In reply to re: Master of the obvious by Ady TZIDON)

Disagree.  We have more answers if the word "positive" is removed, as this allows solutions where all integers are negative.

Posted by Steve Herman on 2016-12-12 19:50:45