proposition: Lemma logn_divz p a b : (0 < a)%N -> b %| a -> ((logn p (a %/ b))%:Z = (logn p a)%:Z - (logn p b)%:Z)%R.
proof: Proof. by move=> ? ?; rewrite logn_div // -subzn // dvdn_leq_log. Qed.
imports: mathcomp(all_ssreflect all_algebra)