a(n) = (2*n^3 + 9*n^2 + n + 24) / 6.

Terms

a(0) =4a(1) =6a(2) =13a(3) =27a(4) =50a(5) =84a(6) =131a(7) =193a(8) =272a(9) =370a(10) =489a(11) =631a(12) =798a(13) =992a(14) =1215a(15) =1469a(16) =1756a(17) =2078a(18) =2437a(19) =2835a(20) =3274a(21) =3756a(22) =4283a(23) =4857a(24) =5480a(25) =6154a(26) =6881a(27) =7663a(28) =8502a(29) =9400