proposition: Lemma fib_gen n: n <= fib n.+1.
proof: Proof. case:n => //; elim => // n IH. by move: (leq_add IH (fib_gt0 (isT:0<n.+1))); rewrite addn1. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path fintype div bigop binomial) mathcomp(prime finset ssralg ssrnum ssrint)