a(n) = Sum_{p|n, p prime} n^prime(n/p).

Terms

a(0) =0a(1) =4a(2) =9a(3) =64a(4) =25a(5) =7992a(6) =49a(7) =2097152a(8) =59049a(9) =100000001000a(10) =121a(12) =169a(16) =289a(18) =361