MathDB
JBMO Shortlist 2021 N1

Source: JBMO Shortlist 2021

July 2, 2022
JuniorBalkanshortlist2021number theoryfactorial

Problem Statement

Find all positive integers a,b,ca, b, c such that ab+1ab + 1, bc+1bc + 1, and ca+1ca + 1 are all equal to factorials of some positive integers.
Proposed by Nikola Velov, Macedonia