a(n) = Sum_{k=1..n} binomial(n,k) * sigma(n,k) * 3^(n-k).

A206766

a(n) = Sum_{k=1..n} binomial(n,k) * sigma(n,k) * 3^(n-k).

Terms

    a(0) =1a(1) =23a(2) =226a(3) =3039a(4) =33306a(5) =594902a(6) =10012010a(7) =220553599a(8) =5170061143a(9) =138942811678

External references