a(n) = Sum_{d|n} sigma_n(d).

Terms

a(0) =1a(1) =6a(2) =29a(3) =291a(4) =3127a(5) =48246a(6) =823545a(7) =16909060a(8) =387459858a(9) =10019533302a(10) =285311670613