Subtriangle of generalized Catalan triangle CM(1,2) = A116880.

Terms

a(0) =1a(1) =3a(2) =7a(3) =13a(4) =29a(5) =41a(6) =67a(7) =147a(8) =195a(9) =247a(10) =381a(11) =829a(12) =1069a(13) =1277a(14) =1545a(15) =2307a(16) =4995a(17) =6339a(18) =7379a(19) =8451a(20) =9975a(21) =14589a(22) =31485a(23) =39549a(24) =45373a(25) =50733a(26) =56829a(27) =66057a(28) =95235a(29) =205059