Generalized Catalan triangle of Riordan type, called C(1,2).

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =3a(5) =1a(6) =13a(7) =13a(8) =5a(9) =1a(10) =67a(11) =67a(12) =27a(13) =7a(14) =1a(15) =381a(16) =381a(17) =157a(18) =45a(19) =9a(20) =1a(21) =2307a(22) =2307a(23) =963a(24) =291a(25) =67a(26) =11a(27) =1a(28) =14589a(29) =14589