Number of Dyck paths of semilength n such that each level has exactly nine peaks or no peaks.

Terms

a(0) =1a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =0a(7) =0a(8) =0a(9) =1a(10) =1a(11) =9a(12) =37a(13) =101a(14) =227a(15) =487a(16) =1019a(17) =2015a(18) =3724a(19) =6528a(20) =11438a(21) =24758a(22) =81106a(23) =330810a(24) =1542486a(25) =7723906a(26) =35765450a(27) =142808117a(28) =494994177a(29) =1533142713