proposition: Lemma fusci_even n a b: Fusci (n.*2) a b = Fusci n (a + b) b.
proof: Proof. by rewrite /Fusci fusc_even fusc_odd mulnDr addnA - mulnDl. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq choice fintype order bigop ssralg) mathcomp(div ssrnum ssrint rat prime path binomial) mathcomp(tuple finset) gaia(fibm)