Triangle related to Catalan triangle: recurrence related to A033877 (Schroeder numbers).

Terms

a(0) =1a(1) =1a(2) =-1a(3) =1a(4) =-2a(5) =0a(6) =1a(7) =-3a(8) =1a(9) =1a(10) =1a(11) =-4a(12) =3a(13) =2a(14) =0a(15) =1a(16) =-5a(17) =6a(18) =2a(19) =-2a(20) =-2a(21) =1a(22) =-6a(23) =10a(24) =0a(25) =-6a(26) =-4a(27) =0a(28) =1a(29) =-7