MathDB
Golden Residue

Source: Iran MO 3rd round 2016 mid-terms - Number Theory P3

September 6, 2016
number theorymodular arithmeticIran

Problem Statement

Let mm be a positive integer. The positive integer aa is called a golden residue modulo mm if gcd(a,m)=1\gcd(a,m)=1 and xxa(modm)x^x \equiv a \pmod m has a solution for xx. Given a positive integer nn, suppose that aa is a golden residue modulo nnn^n. Show that aa is also a golden residue modulo nnnn^{n^n}.
Proposed by Mahyar Sefidgaran