Expansion of e.g.f. 1/(1+Pi/4-arctan(2*x+1)).

Terms

a(0) =1a(1) =1a(2) =0a(3) =-2a(4) =8a(5) =-16a(6) =-112a(7) =1968a(8) =-16896a(9) =55680a(10) =1243392a(11) =-32546304a(12) =427932672a(13) =-1824506880a(14) =-79446663168