a(n) = n(n+7)(n+1)(n^2+2n+12)/120.

Terms

a(0) =2a(1) =9a(2) =27a(3) =66a(4) =141a(5) =273a(6) =490a(7) =828a(8) =1332a(9) =2057a(10) =3069a(11) =4446a(12) =6279a(13) =8673a(14) =11748a(15) =15640a(16) =20502a(17) =26505a(18) =33839a(19) =42714a(20) =53361a(21) =66033a(22) =81006a(23) =98580a(24) =119080a(25) =142857a(26) =170289a(27) =201782a(28) =237771a(29) =278721