Number of 0..n arrays x(0..4) of 5 elements with zero 4th difference.

Terms

a(0) =2a(1) =15a(2) =40a(3) =103a(4) =202a(5) =381a(6) =636a(7) =1033a(8) =1550a(9) =2287a(10) =3212a(11) =4451a(12) =5946a(13) =7869a(14) =10140a(15) =12969a(16) =16238a(17) =20211a(18) =24744a(19) =30147a(20) =36222a(21) =43349a(22) =51296a(23) =60493a(24) =70646a(25) =82267a(26) =95016a(27) =109467a(28) =125206a(29) =142897