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

A120492

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

Terms

    a(0) =2a(1) =6a(2) =39a(3) =504a(4) =17765a(5) =552552a(6) =30870007a(7) =1387350084a(8) =103306557609

External references