Number of 0..n arrays x(0..6) of 7 elements with zero 5th differences.

Terms

a(0) =2a(1) =9a(2) =18a(3) =37a(4) =108a(5) =245a(6) =454a(7) =759a(8) =1172a(9) =2001a(10) =3144a(11) =4663a(12) =6568a(13) =8945a(14) =12690a(15) =17353a(16) =23022a(17) =29787a(18) =37710a(19) =48921a(20) =62130a(21) =77465a(22) =95100a(23) =115177a(24) =141596a(25) =171767a(26) =205850a(27) =244065a(28) =286652a(29) =340277