Number of solutions to +- 1^2 +- 3^2 +- 5^2 +- 7^2 +- ... +- (4*n-1)^2 = 0.

Terms

a(0) =1a(1) =0a(2) =0a(3) =0a(4) =2a(5) =0a(6) =12a(7) =0a(8) =40a(9) =10a(10) =516a(11) =124a(12) =5020a(13) =1828a(14) =48570a(15) =32806a(16) =527890a(17) =444480a(18) =6137942a(19) =6482314a(20) =70573856a(21) =93276044a(22) =853480374a(23) =1300190254a(24) =10660384742a(25) =18371629260a(26) =134129890382a(27) =259804151324