Number of 0..n arrays x(0..4) of 5 elements with zero 3rd differences.

Terms

a(0) =2a(1) =3a(2) =8a(3) =17a(4) =26a(5) =43a(6) =64a(7) =89a(8) =122a(9) =163a(10) =208a(11) =269a(12) =334a(13) =407a(14) =496a(15) =597a(16) =702a(17) =831a(18) =968a(19) =1117a(20) =1286a(21) =1471a(22) =1664a(23) =1889a(24) =2122a(25) =2371a(26) =2648a(27) =2945a(28) =3250a(29) =3595