Number of nondecreasing integer sequences of length 13 with sum zero and sum of absolute values 2n.

Terms

a(0) =1a(1) =4a(2) =9a(3) =25a(4) =49a(5) =121a(6) =224a(7) =476a(8) =862a(9) =1629a(10) =2750a(11) =4942a(12) =7947a(13) =13290a(14) =20892a(15) =33272a(16) =50229a(17) =77373a(18) =113409a(19) =168716a(20) =242193a(21) =349279a(22) =489700a(23) =692174a(24) =950812a(25) =1312535a(26) =1775675a(27) =2406215a(28) =3200557a(29) =4271720