MathDB
Centroamerican Math Olympiad 2017 - P6

Source: OMCC 2017

June 23, 2017
OMCCOMCC 2017CENTROnumber theoryprime numbers

Problem Statement

Tita the Frog sits on the number line. She is initially on the integer number k>1k>1. If she is sitting on the number nn, she hops to the number f(n)+g(n)f(n)+g(n), where f(n)f(n) and g(n)g(n) are, respectively, the biggest and smallest positive prime numbers that divide nn. Find all values of kk such that Tita can hop to infinitely many distinct integers.