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

Terms

a(0) =0a(1) =1a(2) =1a(3) =4a(4) =1a(5) =17a(6) =1a(7) =4a(8) =27a(9) =57a(10) =1a(11) =41a(12) =1a(13) =177a(14) =368a(15) =4a(16) =1a(17) =251a(18) =1a(19) =153a(20) =2530a(21) =2169a(22) =1a(23) =41a(24) =3125a(25) =8361a(26) =27a(27) =561a(28) =1a(29) =5568