Number of hill-free Dyck paths of semilength n+2 and having length of first descent equal to 2 (a hill in a Dyck path is a peak at level 1).
A118973
Number of hill-free Dyck paths of semilength n+2 and having length of first descent equal to 2 (a hill in a Dyck path is a peak at level 1).
Terms
- a(0) =1a(1) =0a(2) =2a(3) =5a(4) =16a(5) =51a(6) =168a(7) =565a(8) =1934a(9) =6716a(10) =23604a(11) =83806a(12) =300154a(13) =1083137a(14) =3934404a(15) =14374413a(16) =52787766a(17) =194746632a(18) =721435884a(19) =2682522918a(20) =10008240456a(21) =37455101382a(22) =140569122624a(23) =528926230530
External references
- oeis: A118973