Number of hill-free Dyck paths of semilength n+3 and having length of first descent equal to 1 (a hill in a Dyck path is a peak at level 1).
A001558
Number of hill-free Dyck paths of semilength n+3 and having length of first descent equal to 1 (a hill in a Dyck path is a peak at level 1).
Terms
- a(0) =1a(1) =3a(2) =10a(3) =33a(4) =111a(5) =379a(6) =1312a(7) =4596a(8) =16266a(9) =58082a(10) =209010a(11) =757259a(12) =2760123a(13) =10114131a(14) =37239072a(15) =137698584a(16) =511140558a(17) =1904038986a(18) =7115422212a(19) =26668376994a(20) =100221202998a(21) =377570383518
External references
- oeis: A001558