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

Terms

a(0) =0a(1) =4a(2) =27a(3) =16a(4) =3125a(5) =252a(6) =823543a(7) =64a(8) =729a(9) =100100a(10) =285311670611a(11) =1872a(13) =105413700a(14) =762750a(15) =256a(17) =6156a(19) =3200400a(20) =1801097802a(23) =14400a(24) =9765625