MathDB
RMM2011, P 2, Day 1 - Find polynomials with integer values

Source:

February 25, 2011
algebrapolynomialmodular arithmeticfunctionnumber theorygreatest common divisorsystem of equations

Problem Statement

Determine all positive integers nn for which there exists a polynomial f(x)f(x) with real coefficients, with the following properties:
(1) for each integer kk, the number f(k)f(k) is an integer if and only if kk is not divisible by nn; (2) the degree of ff is less than nn.
(Hungary) Géza Kós