Expansion of e.g.f. 1/(cos(x) - tan(x)).

Terms

a(0) =1a(1) =1a(2) =3a(3) =14a(4) =81a(5) =616a(6) =5523a(7) =58064a(8) =697281a(9) =9417856a(10) =141368643a(11) =2334020864a(12) =42039523281a(13) =820296426496