G.f.: A(x,q) = sqrt( Q(x,q) / Q(x,-q) ), where Q(x,q) = Sum_{n=-oo..+oo} (x - q^n)^n.

Terms

a(0) =1a(1) =2a(2) =-2a(3) =2a(4) =-4a(5) =2a(6) =2a(7) =-4a(8) =6a(9) =-4a(10) =2a(11) =-4a(12) =8a(13) =-12a(14) =6a(15) =2a(16) =-4a(17) =8a(18) =-14a(19) =16a(20) =-8a(21) =2a(22) =-4a(23) =8a(24) =-12a(25) =18a(26) =-24a(27) =12a(28) =2a(29) =-4