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A004401
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Least number of edges in graph containing all trees on n nodes.
(Formerly M0989)
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5
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OFFSET
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1,3
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COMMENTS
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Paul Tabatabai's program only tests graphs on n nodes, but the term a(9) = 16 is now confirmed. It seems to be sufficient to test only graphs on n vertices (cf. Related Questions, Question 1 in Chung, Graham, and Pippenger). Moreover, if this assumption is true, then the next terms are a(11) = 22 and a(12) = 24. Also note that my program can be used to enumerate all possible solutions. - Manfred Scheucher, Jan 25 2018
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REFERENCES
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R. L. Graham, personal communication.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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F. R. K. Chung, R. L. Graham and N. Pippenger, On graphs which contain all small trees. II. Combinatorics (Proc. Fifth Hungarian Colloq., Keszthely, 1976), Vol. I, pp. 213-223. Colloq. Math. Soc. Janos Bolyai, 18. North-Holland, Amsterdam, 1978.
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CROSSREFS
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KEYWORD
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nonn,nice,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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