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A007859
Number of matchings in rooted plane trees on n nodes.
0
0, 1, 4, 18, 84, 405, 2002, 10101, 51844, 269994, 1423784, 7590044, 40846390, 221650195, 1211606190
OFFSET
1,3
LINKS
M. Klazar, Twelve countings with rooted plane trees, European Journal of Combinatorics 18 (1997), 195-210; Addendum, 18 (1997), 739-740.
CROSSREFS
Sequence in context: A151251 A293490 A010849 * A185132 A085923 A110166
KEYWORD
nonn,more
AUTHOR
STATUS
approved