E.g.f. sec(x)/(1-x) = 1/( cos(x) * (1-x) ).

Terms

a(0) =1a(1) =1a(2) =3a(3) =9a(4) =41a(5) =205a(6) =1291a(7) =9037a(8) =73681a(9) =663129a(10) =6681811a(11) =73499921a(12) =884701817a(13) =11501123621a(14) =161215091675