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A250308
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Number of unlabeled unrooted trees on 2n vertices with all vertices of odd degree.
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2
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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
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1,3
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REFERENCES
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F. Harary and E. Palmer, Graphical Enumeration, Academic Press, 1973, section 3.2.
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LINKS
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EXAMPLE
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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).
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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