|
| |
|
|
A054357
|
|
Number of unlabeled 2-ary cacti having n polygons. Also number of bi-colored plane trees with n edges.
|
|
11
| |
|
|
1, 1, 2, 3, 6, 10, 28, 63, 190, 546, 1708, 5346, 17428, 57148, 191280, 646363, 2210670, 7626166, 26538292, 93013854, 328215300, 1165060668, 4158330416, 14915635378, 53746119972, 194477856100, 706437056648, 2575316704200, 9419571138368
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,3
|
|
|
COMMENTS
| a(n) = the number of inequivalent non-crossing partitions of n points (equally spaced) on a circle, under rotations of the circle. This may be considered the number of non-crossing partitions of n unlabeled points on a circle, so this sequence has the same relation to the Catalan numbers (A000108) as the number of partitions of an integer (A000041) has to the Bell numbers (A000110). - Len Smiley (smiley(AT)math.uaa.alaska.edu), Sep 06 2005
|
|
|
LINKS
| Miklos Bona, Michel Bousquet, Gilbert Labelle and Pierre Leroux, Enumeration of m-ary cacti, Advances in Applied Mathematics, 24 (2000), 22-56 (pdf, dvi).
Index entries for sequences related to cacti
|
|
|
CROSSREFS
| Sequence in context: A123256 A111275 A192440 * A056606 A186408 A062527
Adjacent sequences: A054354 A054355 A054356 * A054358 A054359 A054360
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Simon Plouffe (simon.plouffe(AT)gmail.com)
|
|
|
EXTENSIONS
| More terms from Len Smiley (smiley(AT)math.uaa.alaska.edu), Sep 06 2005
More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Oct 04 2007
|
| |
|
|
