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

Terms

a(0) =0a(1) =0a(2) =0a(3) =2a(4) =6a(5) =18a(6) =70a(7) =310a(8) =1582a(9) =9058a(10) =57678a(11) =403878a(12) =3085478a(13) =25535378a(14) =227589206a(15) =2173314806a(16) =22137209694a(17) =239580726978