proposition: Lemma log2_Sdouble n: log2 (n.*2.+1) = (log2 n).+1.
proof: Proof. case: n => //n;apply: log2_pr. rewrite {1}(log2S_k n) !expn2S ltn_Sdouble leq_Sdouble; exact:(log2_bnd n). 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)