Number of -2..2 arrays of n elements with first through fourth differences also in -2..2.

Terms

a(0) =5a(1) =19a(2) =57a(3) =127a(4) =213a(5) =363a(6) =613a(7) =1055a(8) =1815a(9) =3159a(10) =5503a(11) =9609a(12) =16773a(13) =29281a(14) =51125a(15) =89277a(16) =155899a(17) =272315a(18) =475793a(19) =831415a(20) =1452927a(21) =2539213a(22) =4437877a(23) =7756367a(24) =13556573a(25) =23694815a(26) =41415935a(27) =72391801a(28) =126536987a(29) =221182305