What is the chromatic polynomial P(Cn,k)P(C_n, k)P(Cn,k) for a cycle graph CnC_nCn with nnn vertices?
k(k−1)n−1k(k-1)^{n-1}k(k−1)n−1
kn−1k^n - 1kn−1
(k−1)n+(−1)n(k−1)(k-1)^n + (-1)^n(k-1)(k−1)n+(−1)n(k−1)
kn−k(k−1)k^n - k(k-1)kn−k(k−1)