OFFSET
0,2
REFERENCES
R. Kemp, Balanced ordered trees, Random Structures and Algorithms, 5, 1994, 99-121.
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..500
FORMULA
Conjecture: a(n) ~ 0.721... * 4^n / n. - Vaclav Kotesovec, Aug 25 2014
MAPLE
b:= proc(n, m) option remember; `if`(n=0, 1,
`if`(m=0, add(b(n-j, j), j=1..n),
add(b(n-j, min(n-j, m)), j=1..min(n, m))))
end:
a:= n-> b(2*n, 0):
seq(a(n), n=0..40); # Alois P. Heinz, May 13 2014
MATHEMATICA
b[n_, m_] := b[n, m] = If[n == 0, 1, If[m == 0, Sum[b[n - j, j], {j, 1, n} ], Sum[b[n - j, Min[n - j, m]], {j, 1, Min[n, m]}]]]; a[n_] := b[2*n, 0]; Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Dec 22 2016, after Alois P. Heinz *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Dec 19 2001
EXTENSIONS
More terms from Emeric Deutsch, Jun 10 2004
STATUS
approved