Number of nondecreasing integer sequences of length 22 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) =5926a(12) =10183a(13) =18151a(14) =30727a(15) =52631a(16) =86290a(17) =143571a(18) =229623a(19) =370718a(20) =581639a(21) =914103a(22) =1404106a(23) =2163019a(24) =3260010a(25) =4915632a(26) =7292347a(27) =10798752a(28) =15759648a(29) =22972651