Second column of the extended Catalan triangle A189231.

Terms

a(0) =0a(1) =1a(2) =2a(3) =2a(4) =8a(5) =5a(6) =30a(7) =14a(8) =112a(9) =42a(10) =420a(11) =132a(12) =1584a(13) =429a(14) =6006a(15) =1430a(16) =22880a(17) =4862a(18) =87516a(19) =16796a(20) =335920a(21) =58786a(22) =1293292a(23) =208012a(24) =4992288a(25) =742900a(26) =19315400a(27) =2674440a(28) =74884320a(29) =9694845