Number of nondecreasing integer sequences of length 26 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) =18222a(14) =30958a(15) =53287a(16) =87960a(17) =147491a(18) =238145a(19) =388309a(20) =616169a(21) =979795a(22) =1524774a(23) =2380074a(24) =3639685a(25) =5569074a(26) =8392071a(27) =12625030a(28) =18735698a(29) =27770223