E.g.f.: exp(x) * (sec(x) - tan(x)) / (1 - x).

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =20a(5) =95a(6) =580a(7) =3999a(8) =32272a(9) =288783a(10) =2898300a(11) =31807679a(12) =382253808a(13) =4964649079a(14) =69546528636