Number of 0..n arrays x(0..6) of 7 elements with zero 4th differences.

Terms

a(0) =2a(1) =5a(2) =8a(3) =13a(4) =18a(5) =37a(6) =64a(7) =97a(8) =140a(9) =207a(10) =286a(11) =399a(12) =528a(13) =687a(14) =878a(15) =1127a(16) =1408a(17) =1749a(18) =2130a(19) =2607a(20) =3128a(21) =3743a(22) =4414a(23) =5191a(24) =6056a(25) =7067a(26) =8156a(27) =9387a(28) =10706a(29) =12241