a(n) = (n+1)*(n+3)*(n+8)/6.

Terms

a(0) =0a(1) =4a(2) =12a(3) =25a(4) =44a(5) =70a(6) =104a(7) =147a(8) =200a(9) =264a(10) =340a(11) =429a(12) =532a(13) =650a(14) =784a(15) =935a(16) =1104a(17) =1292a(18) =1500a(19) =1729a(20) =1980a(21) =2254a(22) =2552a(23) =2875a(24) =3224a(25) =3600a(26) =4004a(27) =4437a(28) =4900a(29) =5394