-1686domain: ZAppears in sequencesG.f.: 1-q = Sum_{k>=0} a(k)*q^k*Faq(k+1,q), where Faq(n,q) is the q-factorial of n.at n=13A127926a(n) = Sum_{k<=n} A007955(k) * A008683(n-k+1) = Sum_{k<=n} A007955(k) * mu(n-k+1), where A007955(m) = product of divisors of m.at n=13A174942