The Unfair 0-1 Polynomial Problem and High-Degree Trinomials

The unfair $0$--$1$ polynomial conjecture asks whether a factorization \[C(x)=A(x)B(x),\] with $A$ and $B$ monic and having nonnegative real coefficients, must already be a factorization into $0$--$1$ polynomials. Let $k$ be odd and $0<a<1$. We study the possibility that \[1+a x^2+x^k\] divides a $0$--$1$ polynomial with a nonzero cofactor having nonnegative real coefficients. Ghidelli settled the first nontrivial case $k=5$, and the cases $k=7,9,11$ were treated subsequently by finite recurrence and spectral arguments. We prove that no such factorization exists for any odd $k\ge 341$.