Triangle read by rows: T(n,k) is the number of Dyck paths of semilength n starting with exactly k consecutive pyramids. A pyramid in a Dyck path is a factor of the form U^j D^j (j>0), starting at the x-axis. Here U=(1,1) and D=(1,-1). This definition differs from the one in A091866.
A127156
Triangle read by rows: T(n,k) is the number of Dyck paths of semilength n starting with exactly k consecutive pyramids. A pyramid in a Dyck path is a factor of the form U^j D^j (j>0), starting at the x-axis. Here U=(1,1) and D=(1,-1). This definition differs from the one in A091866.
Terms
- a(0) =1a(1) =0a(2) =1a(3) =0a(4) =1a(5) =1a(6) =1a(7) =1a(8) =2a(9) =1a(10) =5a(11) =2a(12) =3a(13) =3a(14) =1a(15) =19a(16) =7a(17) =5a(18) =6a(19) =4a(20) =1a(21) =67a(22) =26a(23) =12a(24) =11a(25) =10a(26) =5a(27) =1a(28) =232a(29) =93
External references
- oeis: A127156