a(n) = Sum_{j=0..n} sigma_j(n).

Terms

a(0) =2a(1) =10a(2) =44a(3) =377a(4) =3912a(5) =57214a(6) =960808a(7) =19261862a(8) =435877584a(9) =11123320200a(10) =313842837684