1784161domain: NAppears in sequencesa(n) = n! * Sum_{d|n} mu(d) / d!.at n=9A332466Expansion of e.g.f. exp(x * (1 - x^4)).at n=10A351906a(n) = n! * Sum_{d|n} mu(n/d) / d!.at n=9A354022