G.f.: A(x) = 1 + x/Series_Reversion(eta(x) - 1).

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =19a(5) =64a(6) =223a(7) =799a(8) =2927a(9) =10922a(10) =41382a(11) =158800a(12) =615939a(13) =2410880a(14) =9510650a(15) =37774357a(16) =150929671a(17) =606239784a(18) =2446566976a(19) =9915210221a(20) =40336587662a(21) =164662328192a(22) =674300310836