MathDB
MTRP SUBJECTIVE Q5

Source: MTRP 2024

March 16, 2024
algebra

Problem Statement

Let f:NNf:\mathbb{N} \longrightarrow \mathbb{N} such that f(m)f(n)=f(mn)10nm>nNf(m) - f(n) = f(m-n)10^n \forall m>n \in \mathbb{N}. Additionally, gcd(f(k),f(k+1))=1kN(f(k),f(k+1)) = 1 \forall k \in \mathbb{N}. Show that if a,ba,b are coprime natural numbers, that is, gcd(a,b)=1(a,b) = 1 then f(a),f(b)f(a),f(b) are also coprime.