proposition: Lemma fusci_odd n a b: Fusci (n.*2.+1) a b = Fusci n a (a + b).
proof: Proof. by rewrite /Fusci - doubleS 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)