proposition: Lemma fusc_kpow2n k n : fusc (2 ^ n * k) = fusc k.
proof: Proof. by elim: n k => [k | n Hr k]; rewrite ?mul1n // expnS - mulnA mul2n fusc_even. 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)