IMO 2022 Shortlist A7

For a positive integer n we denote by spnq the sum of the digits of n. Let Ppxq “ xn an´1xn´1 ¨¨¨a1xa0 be a polynomial, ...

IMO 2022 Shortlist A7

Category: Algebra

Problem

For a positive integer n we denote by spnq the sum of the digits of n. Let Ppxq “ xn an´1xn´1 ¨¨¨a1xa0 be a polynomial, where n ě 2 and ai is a positive integer for all 0 ď i ď n ´ 1. Could it be the case that, for all positive integers k, spkq and spPpkqq have the same parity? (Belarus)