proposition: Lemma half_le3 m: 1 < m -> (m.+1)./2 < m.
proof: Proof. by case: m => [|[|n _]] //;rewrite ltnS ltnS half_le2. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path fintype div bigop binomial) mathcomp(prime finset ssralg ssrnum ssrint)