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A078792
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Number of unlabeled 3-trees on n vertices.
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2
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0, 0, 1, 1, 1, 2, 5, 15, 58, 275, 1505, 9003, 56931, 372973, 2506312, 17165954, 119398333, 841244274, 5993093551, 43109340222, 312747109787, 2286190318744, 16826338257708, 124605344758149, 927910207739261, 6945172081954449, 52225283886702922
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,6
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COMMENTS
| A k-tree is recursively defined as follows: K_k is a k-tree and any k-tree on n+1 vertices is obtained by joining a new vertex to a k-clique in a k-tree on n vertices.
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CROSSREFS
| Cf. A036362(labeled 3-trees), A054581 (unlabeled 2-trees).
Sequence in context: A005976 A187981 A048192 * A030934 A030922 A030916
Adjacent sequences: A078789 A078790 A078791 * A078793 A078794 A078795
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KEYWORD
| nonn
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AUTHOR
| Gordon Royle (gordon(AT)maths.uwa.edu.au), Dec 05 2002
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EXTENSIONS
| More terms from Andrew R. Gainer (againer(AT)brandeis.edu), Dec 03 2011
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