MathDB
a polynomial

Source: 2011-2012 china second round,problem 2

October 30, 2011
algebrapolynomialgeometrygeometric transformationnumber theory proposednumber theory

Problem Statement

For any integer n4n\ge 4, prove that there exists a nn-degree polynomial f(x)=xn+an1xn1++a0f(x)=x^n+a_{n-1}x^{n-1}+\cdots+a_0 satisfying the two following properties:
(1) aia_i is a positive integer for any i=0,1,,n1i=0,1,\ldots,n-1, and
(2) For any two positive integers mm and kk (k2k\ge 2) there exist distinct positive integers r1,r2,...,rkr_1,r_2,...,r_k, such that f(m)i=1kf(ri)f(m)\ne\prod_{i=1}^{k}f(r_i).