T(n,k)=Number of -k..k arrays of n elements with first and second differences also in -k..k.

Terms

a(0) =3a(1) =5a(2) =7a(3) =7a(4) =19a(5) =13a(6) =9a(7) =37a(8) =57a(9) =25a(10) =11a(11) =61a(12) =153a(13) =175a(14) =47a(15) =13a(16) =91a(17) =323a(18) =651a(19) =537a(20) =89a(21) =15a(22) =127a(23) =587a(24) =1759a(25) =2771a(26) =1653a(27) =169a(28) =17a(29) =169