OFFSET
0,2
COMMENTS
Compare to A073147. Related to generalized Catalan numbers; in particular, C(3n,n)/(2n+1) (enumerates ternary trees and also non-crossing trees)(A001764).
These numbers are cardinalities of some intervals in the Tamari lattices. - F. Chapoton, Jul 15 2021
FORMULA
a(n, m) = Sum A001764(n-k)*a(n, k), k=0..m.
EXAMPLE
{1}, {2,3}, {7,9,12}, {30,37,43,55}, {143,173,194,218,273},{728,871,961,1045,1155,1428}, {3876,4604,5033,5393,5778,6324,7752}, ...
CROSSREFS
KEYWORD
AUTHOR
Paul D. Hanna, Jul 18 2002
STATUS
approved