proposition: Lemma log2_double n: log2 ((n.+1).*2) = (log2 n.+1).+1.
proof: Proof. apply: log2_pr. rewrite {1} (log2S_k n) !expn2S ltn_double leq_double; 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)