Number of nondecreasing integer sequences of length 17 with sum zero and sum of absolute values 2n.

Terms

a(0) =1a(1) =4a(2) =9a(3) =25a(4) =49a(5) =121a(6) =225a(7) =484a(8) =899a(9) =1756a(10) =3098a(11) =5790a(12) =9779a(13) =17092a(14) =28252a(15) =47222a(16) =75258a(17) =121818a(18) =188762a(19) =295544a(20) =448275a(21) =681330a(22) =1009650a(23) =1502269a(24) =2181026a(25) =3170981a(26) =4528407a(27) =6459739a(28) =9066916a(29) =12725984