a(n) = n * (binomial(n + 1, 3) + 1).

Terms

a(0) =0a(1) =1a(2) =4a(3) =15a(4) =44a(5) =105a(6) =216a(7) =399a(8) =680a(9) =1089a(10) =1660a(11) =2431a(12) =3444a(13) =4745a(14) =6384a(15) =8415a(16) =10896a(17) =13889a(18) =17460a(19) =21679a(20) =26620a(21) =32361a(22) =38984a(23) =46575a(24) =55224a(25) =65025a(26) =76076a(27) =88479a(28) =102340a(29) =117769