Number of nondecreasing arrangements of n numbers in -5..5 with sum zero.

Terms

a(0) =1a(1) =6a(2) =18a(3) =55a(4) =141a(5) =338a(6) =734a(7) =1514a(8) =2934a(9) =5448a(10) =9686a(11) =16660a(12) =27718a(13) =44916a(14) =70922a(15) =109583a(16) =165821a(17) =246448a(18) =360002a(19) =517971a(20) =734517a(21) =1028172a(22) =1421530a(23) =1943488a(24) =2628824a(25) =3521260a(26) =4672836a(27) =6147894a(28) =8022362a(29) =10388788