Definition Bessel1 (n : nat) (x : R) :=
  (x/2)^n * PSeries (Bessel1_seq n) ((x/2)^2).

Lemma Bessel1_uniqueness_aux_0 (a : nat -> R) (n : nat) : Rbar_lt 0 (CV_radius a) -> (forall x : R, Rbar_lt (Rabs x) (CV_radius a) -> x^2 * Derive_n (PSeries a) 2 x + x * Derive (PSeries a) x + (x^2 - (INR n)^2) * PSeries a x = 0) -> (a 0%nat = 0 \/ n = O) /\ (a 1%nat = 0 \/ n = 1%nat) /\ (forall k, (INR (S (S k)) ^ 2 - INR n ^ 2) * a (S (S k)) + a k = 0).