a(n) = Sum_{d|n} d*binomial(d+2,3).

Terms

a(0) =1a(1) =9a(2) =31a(3) =89a(4) =176a(5) =375a(6) =589a(7) =1049a(8) =1516a(9) =2384a(10) =3147a(11) =4823a(12) =5916a(13) =8437a(14) =10406a(15) =14105a(16) =16474a(17) =22380a(18) =25271a(19) =33264a(20) =37810a(21) =47683a(22) =52901a(23) =68183a(24) =73301a(25) =91100a(26) =100174a(27) =122197a(28) =130356a(29) =161750