E.g.f.: exp(1 / (1 - sinh(x)) - 1).

Terms

a(0) =1a(1) =1a(2) =3a(3) =14a(4) =85a(5) =632a(6) =5559a(7) =56352a(8) =645929a(9) =8252352a(10) =116189291a(11) =1786361216a(12) =29764770941a(13) =534082233856