a(n) = n*(n+1)*(n+2)*(n+3)/4.

Terms

a(0) =0a(1) =6a(2) =30a(3) =90a(4) =210a(5) =420a(6) =756a(7) =1260a(8) =1980a(9) =2970a(10) =4290a(11) =6006a(12) =8190a(13) =10920a(14) =14280a(15) =18360a(16) =23256a(17) =29070a(18) =35910a(19) =43890a(20) =53130a(21) =63756a(22) =75900a(23) =89700a(24) =105300a(25) =122850a(26) =142506a(27) =164430a(28) =188790a(29) =215760