Number of -n..n arrays x(0..4) of 5 elements with zero sum and nonzero second differences.

Terms

a(0) =26a(1) =280a(2) =1184a(3) =3396a(4) =7778a(5) =15476a(6) =27806a(7) =46346a(8) =72902a(9) =109528a(10) =158422a(11) =222162a(12) =303412a(13) =405134a(14) =530518a(15) =683014a(16) =866156a(17) =1083954a(18) =1340420a(19) =1639900a(20) =1986968a(21) =2386470a(22) =2843276a(23) =3362828a(24) =3950486a(25) =4611980a(26) =5353268a(27) =6180592a(28) =7100158a(29) =8118840