Number of nondecreasing integer sequences of length 29 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) =30975a(15) =53353a(16) =88171a(17) =148086a(18) =239666a(19) =391914a(20) =624144a(21) =996519a(22) =1558110a(23) =2444206a(24) =3758817a(25) =5785219a(26) =8774142a(27) =13288255a(28) =19862807a(29) =29658474