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

Terms

a(0) =0a(1) =1a(2) =2a(3) =6a(4) =28a(5) =160a(6) =1086a(7) =8624a(8) =78296a(9) =799488a(10) =9070810a(11) =113208832a(12) =1541351604a(13) =22734473216a(14) =361121134934