a(n) = phi(n) * (sigma(n) - n).

Terms

a(0) =0a(1) =1a(2) =2a(3) =6a(4) =4a(5) =12a(6) =6a(7) =28a(8) =24a(9) =32a(10) =10a(11) =64a(12) =12a(13) =60a(14) =72a(15) =120a(16) =16a(17) =126a(18) =18a(19) =176a(20) =132a(21) =140a(22) =22a(23) =288a(24) =120a(25) =192a(26) =234a(27) =336a(28) =28a(29) =336