proposition: Lemma lucas3S n: lucas n.+3 = (lucas n.+1).*2 + (lucas n).
proof: Proof. by rewrite !lucasSS addnAC addnn. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path fintype div bigop binomial) mathcomp(prime finset ssralg ssrnum ssrint)