Carlitz-Riordan q-Catalan numbers (recurrence version) for q = -1.

Terms

a(0) =1a(1) =1a(2) =0a(3) =-1a(4) =0a(5) =2a(6) =0a(7) =-5a(8) =0a(9) =14a(10) =0a(11) =-42a(12) =0a(13) =132a(14) =0a(15) =-429a(16) =0a(17) =1430a(18) =0a(19) =-4862a(20) =0a(21) =16796a(22) =0a(23) =-58786a(24) =0a(25) =208012a(26) =0a(27) =-742900a(28) =0a(29) =2674440