a(n) = Sum_{k=1..n} gcd(n,k)^n.

Terms

a(0) =1a(1) =5a(2) =29a(3) =274a(4) =3129a(5) =47515a(6) =823549a(7) =16843268a(8) =387459861a(9) =10009769725a(10) =285311670621