MathDB
Iterated Integer Polynomial modulo n

Source: 2021 ISL N8

July 12, 2022
algebrapolynomialceiling functionabstract algebra

Problem Statement

Find all positive integers nn for which there exists a polynomial P(x)Z[x]P(x) \in \mathbb{Z}[x] such that for every positive integer m1m\geq 1, the numbers Pm(1),,Pm(n)P^m(1), \ldots, P^m(n) leave exactly n/2m\lceil n/2^m\rceil distinct remainders when divided by nn. (Here, PmP^m means PP applied mm times.)
Proposed by Carl Schildkraut, USA