MathDB
An Order Identity

Source: Indonesian Stage 1 TST for IMO 2022, Test 3 (Number Theory)

December 25, 2021
Ordernumber theoryidentityDivisibility

Problem Statement

Given positive odd integers mm and nn where the set of all prime factors of mm is the same as the set of all prime factors nn, and nmn \vert m. Let aa be an arbitrary integer which is relatively prime to mm and nn. Prove that: om(a)=on(a)×mgcd(m,aon(a)1) o_m(a) = o_n(a) \times \frac{m}{\gcd(m, a^{o_n(a)}-1)} where ok(a)o_k(a) denotes the smallest positive integer such that aok(a)1a^{o_k(a)} \equiv 1 (mod kk) holds for some natural number k>1k > 1.