Half the number of length n integer sequences with sum zero and sum of squares 8.

Terms

a(0) =1a(1) =3a(2) =6a(3) =30a(4) =135a(5) =441a(6) =1183a(7) =2871a(8) =6660a(9) =15070a(10) =33231a(11) =70863a(12) =145236a(13) =285390a(14) =537930a(15) =974746a(16) =1703043a(17) =2878101a(18) =4719220a(19) =7529340a(20) =11718861a(21) =17834223a(22) =26591841a(23) =38918025a(24) =55995550a(25) =79317576a(26) =110749653a(27) =152600581a(28) =207702930a(29) =279504060