proposition: Lemma N_of_bitseq_true p : N.to_nat (N_of_bitseq (true :: nseq p false)) = 2 ^ p.
proof: Proof. elim : p => // p IH /=. by rewrite (_ : false :: _ = nseq p.+1 false) // rev_nseq pos_of_bitseq_nseq_false. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype tuple) BinPos BinNat PArith ssr_ext