a(n) = (n^4 + 5*n^3 + 11*n^2 + 7*n)/6.

Terms

a(0) =0a(1) =4a(2) =19a(3) =56a(4) =130a(5) =260a(6) =469a(7) =784a(8) =1236a(9) =1860a(10) =2695a(11) =3784a(12) =5174a(13) =6916a(14) =9065a(15) =11680a(16) =14824a(17) =18564a(18) =22971a(19) =28120a(20) =34090a(21) =40964a(22) =48829a(23) =57776a(24) =67900a(25) =79300a(26) =92079a(27) =106344a(28) =122206a(29) =139780