a(n) = sigma[k](n) - phi(n)^k - d(n)^k for k=3.

Terms

a(0) =-1a(1) =0a(2) =12a(3) =38a(4) =54a(5) =180a(6) =120a(7) =457a(8) =514a(9) =1006a(10) =324a(11) =1764a(12) =462a(13) =2816a(14) =2952a(15) =4044a(16) =810a(17) =6381a(18) =1020a(19) =8470a(20) =7840a(21) =10924a(22) =1512a(23) =15356a(24) =7724a(25) =17990a(26) =14544a(27) =23168a(28) =2430a(29) =30728