Problem 4
Source: Last round of the Bulgarian Mathematical Oympiad 2009
June 18, 2009
algebrapolynomialalgebra proposed
Problem Statement
Let be a natural number. Find all nonconstant polynomials with real coeficcietns , for which
f_{k}\left(x\right)f_{k+ 1}\left(x\right) = f_{k +1}\left(f_{k + 2}\left(x\right)\right), 1\le k\le n,
for every real (with and ).