induction n; intuition; simpl in *.
rewrite IHn.
trivial.
Qed.
Fixpoint getAllBlists(n : nat) : (list Blist) :=
match n with
| 0 => nil :: nil
| S n' => (map (cons true) (getAllBlists n')) ++
(map (cons false) (getAllBlists n'))
end.
Fixpoint getAllBlists_app(n : nat) : list Blist :=
match n with
| 0 => nil :: nil
| S n' => (map (fun ls => ls ++ (true :: nil)) (getAllBlists_app n')) ++
(map (fun ls => ls ++ (false :: nil)) (getAllBlists_app n'))
end.
Fixpoint getAllBvectors(n : nat) : (list (Bvector n)) :=
match n with
| 0 => (Vector.nil bool) :: nil
| S n' => (map (Vector.cons _ true _) (getAllBvectors n')) ++
(map (Vector.cons _ false _) (getAllBvectors n'))
end.

(* Specifications: *)
Lemma getAllBvectors_length : forall n,
length (getAllBvectors n) = (expnat 2 n).