1 + Sum[ k^(n-1), {k,1,n}].

A120490

1 + Sum[ k^(n-1), {k,1,n}].

Terms

    a(0) =2a(1) =4a(2) =15a(3) =101a(4) =980a(5) =12202a(6) =184821a(7) =3297457a(8) =67731334a(9) =1574304986a(10) =40851766527

External references