Number of nondecreasing integer sequences of length 33 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) =10201a(13) =18225a(14) =30976a(15) =53361a(16) =88208a(17) =148217a(18) =240062a(19) =392990a(20) =626830a(21) =1002789a(22) =1571895a(23) =2473080a(24) =3816573a(25) =5896723a(26) =8982257a(27) =13667085a(28) =20535209a(29) =30829927