OFFSET
0,4
COMMENTS
This is the number of nonzero, non-constant terms of the polynomials M_n(x) Donaghey gives on the page 81 of his paper. The term x^18 seems to have been accidentally dropped from the polynomial M_7(x).
LINKS
Robert Donaghey, Automorphisms on Catalan trees and bracketing, J. Combin. Theory, Series B, 29 (1980), 75-90.
Antti Karttunen, Counted with the help of this C program.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Wouter Meeussen and Antti Karttunen, Mar 10 2003
STATUS
approved