Expansion of g.f. A(x) = Sum_{n=-oo..+oo} x^n * (i + x^n)^(2*n), where i^2 = -1.

Terms

a(0) =1a(1) =0a(2) =1a(3) =-3a(4) =1a(5) =4a(6) =-4a(7) =-8a(8) =1a(9) =23a(10) =-8a(11) =-12a(12) =-27a(13) =12a(14) =36a(15) =15a(16) =1a(17) =16a(18) =-149a(19) =-20a(20) =71a(21) =91a(22) =166a(23) =-24a(24) =-119a(25) =-186a(26) =-285a(27) =251a(28) =-26a(29) =28