Number of nondecreasing integer sequences of length 25 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) =900a(9) =1764a(10) =3136a(11) =5929a(12) =10200a(13) =18217a(14) =30938a(15) =53222a(16) =87775a(17) =147014a(18) =237016a(19) =385812a(20) =610985a(21) =969505a(22) =1505188a(23) =2343756a(24) =3574348a(25) =5453815a(26) =8193561a(27) =12288418a(28) =18176135a(29) =26851525