(* 3^e in GF(2^8) *)
Definition exp3 (e: nat): int := ff_exp (Int.repr 3) (Int.repr (Z.of_nat e)).

Lemma gen_exp_table_correct : forall n : nat, (n <= 256)%nat -> forall i : nat, (i < n)%nat -> nth i (gen_exp_table n (exp3 (256-n))) Int.zero = exp3 (256+i-n).