intros w; induction w.
- intros n; destruct n; simpl; norm.
- intros n.
destruct n; norm.
Qed.

Lemma gen_phiNword_Nwcons : forall w n,
gen_phiNword (Nwcons n w) == gen_phiN rO rI radd rmul n - gen_phiNword w.