ChromaticPolynomial
ChromaticPolynomial[g, k] gives the chromatic polynomial of the graph g.
ChromaticPolynomial[{v -> w, ...}, k] uses rules to specify the graph g.
Examples
Chromatic polynomial of a complete graph:
ChromaticPolynomial[CompleteGraph[4], k]
(* k (k - 1) (k - 2) (k - 3) *)Chromatic polynomial of a cycle:
ChromaticPolynomial[CycleGraph[5], k]
(* (k - 1)^5 + (k - 1) *)Please visit the official Wolfram Language Reference for more details.