Number of solutions to +- 1 +- 2 +- .. +- n = 2.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =2a(5) =0a(6) =0a(7) =8a(8) =13a(9) =0a(10) =0a(11) =69a(12) =123a(13) =0a(14) =0a(15) =719a(16) =1313a(17) =0a(18) =0a(19) =8215a(20) =15260a(21) =0a(22) =0a(23) =99774a(24) =187615a(25) =0a(26) =0a(27) =1264854a(28) =2399207a(29) =0