Number of skew Dyck paths of semilength n having no LL's.

Terms

a(0) =1a(1) =1a(2) =3a(3) =9a(4) =30a(5) =107a(6) =399a(7) =1537a(8) =6069a(9) =24434a(10) =99924a(11) =413943a(12) =1733394a(13) =7325471a(14) =31203159a(15) =133825441a(16) =577418430a(17) =2504681465a(18) =10916208453a(19) =47778816718a(20) =209923718880a(21) =925537620996