Number of zero-sum -n..n arrays of 5 elements with first and second differences also in -n..n.

Terms

a(0) =5a(1) =45a(2) =169a(3) =443a(4) =977a(5) =1905a(6) =3373a(7) =5555a(8) =8655a(9) =12901a(10) =18541a(11) =25891a(12) =35207a(13) =46827a(14) =61141a(15) =78483a(16) =99295a(17) =124019a(18) =153047a(19) =186915a(20) =226123a(21) =271207a(22) =322711a(23) =381229a(24) =447347a(25) =521711a(26) =605043a(27) =697945a(28) =801117a(29) =915391