Number of zero-sum -n..n arrays of 5 elements with adjacent element differences also in -n..n.

Terms

a(0) =15a(1) =107a(2) =397a(3) =1077a(4) =2385a(5) =4643a(6) =8211a(7) =13533a(8) =21091a(9) =31461a(10) =45241a(11) =63135a(12) =85861a(13) =114251a(14) =149145a(15) =191501a(16) =242277a(17) =302561a(18) =373433a(19) =456105a(20) =551777a(21) =661793a(22) =787469a(23) =930277a(24) =1091655a(25) =1273201a(26) =1476475a(27) =1703201a(28) =1955057a(29) =2233899