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

Terms

a(0) =0a(1) =1a(2) =1a(3) =0a(4) =0a(5) =3a(6) =5a(7) =0a(8) =0a(9) =23a(10) =40a(11) =0a(12) =0a(13) =221a(14) =397a(15) =0a(16) =0a(17) =2410a(18) =4441a(19) =0a(20) =0a(21) =28460a(22) =53222a(23) =0a(24) =0a(25) =353743a(26) =668273a(27) =0a(28) =0a(29) =4559828