Friendly numbers
Source: Cono Sur Olympiad 2016, problem 6
August 28, 2017
number theorycono sur
Problem Statement
We say that three different integers are friendly if one of them divides the product of the other two. Let be a positive integer.a) Show that, between and , exclusive, does not exist any triplet of friendly numbers.b) Determine if for each exists a triplet of friendly numbers between and , exclusive.