a(n) = sigma_3(n) - sigma_2(n) - sigma_1(n).

Terms

a(0) =-1a(1) =1a(2) =14a(3) =45a(4) =94a(5) =190a(6) =286a(7) =485a(8) =653a(9) =986a(10) =1198a(11) =1806a(12) =2014a(13) =2822a(14) =3244a(15) =4309a(16) =4606a(17) =6319a(18) =6478a(19) =8610a(20) =9100a(21) =11342a(22) =11614a(23) =15470a(24) =15069a(25) =18890a(26) =19580a(27) =24006a(28) =23518a(29) =30380