a(n) = n*(n + 1)*(n + 2)*(3*n + 17)/24.

Terms

a(0) =0a(1) =5a(2) =23a(3) =65a(4) =145a(5) =280a(6) =490a(7) =798a(8) =1230a(9) =1815a(10) =2585a(11) =3575a(12) =4823a(13) =6370a(14) =8260a(15) =10540a(16) =13260a(17) =16473a(18) =20235a(19) =24605a(20) =29645a(21) =35420a(22) =41998a(23) =49450a(24) =57850a(25) =67275a(26) =77805a(27) =89523a(28) =102515a(29) =116870