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

Terms

a(0) =0a(1) =6a(2) =24a(3) =66a(4) =120a(5) =240a(6) =336a(7) =570a(8) =744a(9) =1116a(10) =1320a(11) =2016a(12) =2184a(13) =3072a(14) =3504a(15) =4650a(16) =4896a(17) =6774a(18) =6840a(19) =9156a(20) =9600a(21) =11952a(22) =12144a(23) =16320a(24) =15720a(25) =19740a(26) =20400a(27) =25056a(28) =24360a(29) =31680