proposition: Lemma size_sternD u v n: size (sternD u v n) = (2^n).+1.
proof: Proof. elim:n => // n Hr. rewrite expn2S - [RHS] /(((2 ^ n).+1).*2.-1) - Hr /=. by elim: (sternD u v n) => // c [] // d l /= ->. 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)