MathDB
Cono Sur Olympiad 2013, Problem 5

Source:

August 22, 2014
number theory proposednumber theory

Problem Statement

Let d(k)d(k) be the number of positive divisors of integer kk. A number nn is called balanced if d(n1)d(n)d(n+1)d(n-1) \leq d(n) \leq d(n+1) or d(n1)d(n)d(n+1)d(n-1) \geq d(n) \geq d(n+1). Show that there are infinitely many balanced numbers.