A081164 Number of distinct cycle lengths in range [A014137(n-1)..A014138(n-1)] of permutation A057505/A057506.

1, 1, 1, 2, 2, 4, 4, 11, 15, 25, 32, 64, 88, 155, 234, 423, 647, 1184, 1800

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

Table of n, a(n) for n=0..18.

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

Cf. A081166, A060114.

Sequence in context: A209284 A321468 A288044 * A125553 A218147 A226978

Adjacent sequences: A081161 A081162 A081163 * A081165 A081166 A081167

Keyword

nonn,more

Author

Wouter Meeussen and Antti Karttunen, Mar 10 2003

Status

approved