Catalan numbers (A000108) interpolated with 0's.

Terms

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