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Search: id:A058866
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| A058866 |
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Number of 2-trees rooted at a edge. |
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+0
8
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| 1, 2, 6, 21, 83, 356, 1599, 7434, 35381, 171508, 843419, 4197179, 21094355, 106915928, 545859112, 2804656069, 14491370996, 75248398034, 392476363133, 2055245992376, 10801442696736, 56953957110855, 301207378815752
(list; graph; listen)
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OFFSET
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1,2
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REFERENCES
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F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 75, Eq. (3.5.11).
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FORMULA
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H. and P. give g.f.
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CROSSREFS
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Let A063687(n) be the number of 2-trees rooted at a symmetric edge (see H. and P. Eq. (3.5.9)). Then A058866(n) = A058870(n) + A063687(n).
Cf. A058870, A058870, A054581.
Sequence in context: A148495 A150221 A063689 this_sequence A087649 A150222 A150223
Adjacent sequences: A058863 A058864 A058865 this_sequence A058867 A058868 A058869
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Jan 06 2001
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EXTENSIONS
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More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 22 2001
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