MathDB
IMO Shortlist 2012, Number Theory 5

Source: IMO Shortlist 2012, Number Theory 5

July 29, 2013
algebranumber theoryIMO Shortlistprime numberspolynomial

Problem Statement

For a nonnegative integer nn define rad(n)=1\operatorname{rad}(n)=1 if n=0n=0 or n=1n=1, and rad(n)=p1p2pk\operatorname{rad}(n)=p_1p_2\cdots p_k where p1<p2<<pkp_1<p_2<\cdots <p_k are all prime factors of nn. Find all polynomials f(x)f(x) with nonnegative integer coefficients such that rad(f(n))\operatorname{rad}(f(n)) divides rad(f(nrad(n)))\operatorname{rad}(f(n^{\operatorname{rad}(n)})) for every nonnegative integer nn.