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

Terms

a(0) =0a(1) =0a(2) =1a(3) =0a(4) =0a(5) =3a(6) =5a(7) =0a(8) =0a(9) =23a(10) =39a(11) =0a(12) =0a(13) =219a(14) =396a(15) =0a(16) =0a(17) =2406a(18) =4435a(19) =0a(20) =0a(21) =28431a(22) =53167a(23) =0a(24) =0a(25) =353500a(26) =667874a(27) =0a(28) =0a(29) =4557831