proposition: Lemma cle_Sn_doublen n: natp n -> n <> \0c -> csucc n <=c cdouble n.
proof: Proof. move => nN /(cpred_pr nN) [sa ->]. rewrite (double_succ sa);apply: cleSS; apply: cleSS; apply:(cle_n_doublen sa). Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(binomial div)