Number of solutions to +-1^2 +- 2^2 +- 3^2 +- ... +- n^2 = 0 or 1.

Terms

a(0) =1a(1) =1a(2) =0a(3) =0a(4) =0a(5) =0a(6) =2a(7) =2a(8) =2a(9) =5a(10) =2a(11) =2a(12) =10a(13) =13a(14) =43a(15) =86a(16) =114a(17) =193a(18) =274a(19) =478a(20) =860a(21) =1552a(22) =3245a(23) =5808a(24) =10838a(25) =18628a(26) =31048a(27) =55626a(28) =100426a(29) =188536