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

Terms

a(0) =1a(1) =1a(2) =2a(3) =8a(4) =40a(5) =264a(6) =2048a(7) =18864a(8) =196992a(9) =2330112a(10) =30519552a(11) =440998656a(12) =6940852224a(13) =118501542912