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

Terms

a(0) =0a(1) =2a(2) =3a(3) =2a(4) =5a(5) =7a(6) =7a(7) =4a(8) =9a(9) =21a(10) =11a(11) =13a(12) =13a(13) =71a(14) =106a(15) =16a(16) =17a(17) =73a(18) =19a(19) =41a(20) =778a(21) =1035a(22) =23a(23) =97a(24) =625a(25) =4109a(26) =729a(27) =113a(28) =29a(29) =362