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A063689
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Number of 2-trees rooted at a triangle with 3 similar edges.
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0
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1, 1, 2, 6, 21, 83, 356, 1599, 7434, 35381, 171508, 843419, 4197179, 21094355
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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REFERENCES
| F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 76, Eq. (3.5.17).
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EXAMPLE
| Sequence really begins 1, 0, 0, 1, 0, 0, 2, 0, 0, 6, 0, 0, 21, 0, 0, 83, 0, 0, 356, ... but only nonzero trisection is shown.
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CROSSREFS
| Cf. A005750, A058870, A058866, A054581.
Sequence in context: A032346 A148495 A150221 * A058866 A178325 A087649
Adjacent sequences: A063686 A063687 A063688 * A063690 A063691 A063692
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KEYWORD
| more,nonn
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AUTHOR
| Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 22 2001
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