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

Terms

a(0) =1a(1) =0a(2) =1a(3) =6a(4) =41a(5) =340a(6) =3361a(7) =38682a(8) =508241a(9) =7506504a(10) =123108961a(11) =2219822990a(12) =43648348985a(13) =929502984540