Number of nondecreasing arrangements of 4 nonzero numbers in -(n+2)..(n+2) with sum zero.

Terms

a(0) =10a(1) =20a(2) =37a(3) =61a(4) =94a(5) =136a(6) =191a(7) =257a(8) =338a(9) =434a(10) =547a(11) =677a(12) =828a(13) =998a(14) =1191a(15) =1407a(16) =1648a(17) =1914a(18) =2209a(19) =2531a(20) =2884a(21) =3268a(22) =3685a(23) =4135a(24) =4622a(25) =5144a(26) =5705a(27) =6305a(28) =6946a(29) =7628