Number of Dyck paths of semilength n avoiding the pattern U^3 D^3 U D.

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =13a(5) =28a(6) =48a(7) =73a(8) =103a(9) =138a(10) =178a(11) =223a(12) =273a(13) =328a(14) =388a(15) =453a(16) =523a(17) =598a(18) =678a(19) =763a(20) =853a(21) =948a(22) =1048a(23) =1153a(24) =1263a(25) =1378a(26) =1498a(27) =1623a(28) =1753a(29) =1888