

A250308


Number of unlabeled unrooted trees on 2n vertices with all vertices of odd degree.


2



1, 1, 2, 3, 7, 13, 32, 74, 192, 497, 1379, 3844, 11111, 32500, 96977, 292600, 894353, 2758968, 8590147, 26947946, 85138589, 270646644, 865260519, 2780393959, 8976443582, 29104709339, 94741504408, 309529405055, 1014690513653, 3336805406462, 11005284876792
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OFFSET

1,3


REFERENCES

F. Harary and E. Palmer, Graphical Enumeration, Academic Press, 1973, section 3.2.


LINKS

Table of n, a(n) for n=1..31.
StackExchange, Trees with odd degree sequence.


EXAMPLE

When n=2 we have four vertices in the tree and the path graph does not qualify, as it contains two nodes of degree two, but the star with a center node connected to three neighboring nodes qualifies (degrees three and one are both odd).


CROSSREFS

Sequence in context: A032131 A324844 A007827 * A259145 A237255 A129859
Adjacent sequences: A250305 A250306 A250307 * A250309 A250310 A250311


KEYWORD

nonn


AUTHOR

Marko Riedel, Jan 15 2015


STATUS

approved



