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 A003323 Multicolor Ramsey numbers R(3,3,...,3), where there are n 3's. (Formerly M2594) 3
 3, 6, 17, 62, 327 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Definition: if the edges of a complete graph with at least a(n) nodes are colored with n colors then there is always a monochromatic triangle, and a(n) is the smallest number with this property. Has it been proved that a(4)=62, or is it just an upper bound? - N. J. A. Sloane, Jun 12 2016 62 is an upper bound.  It is probably not the correct value, which is likely closer to the lower bound of 51. - Jeremy F. Alm, Jun 12 2016 REFERENCES G. Berman and K. D. Fryer, Introduction to Combinatorics. Academic Press, NY, 1972, p. 175. S. Fettes, R. Kramer, S. Radziszowski, An upper bound of 62 on the classical Ramsey number R(3,3,3,3), Ars Combin. 72 (2004), 41-63. H. W. Gould, personal communication. N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS R. E. Greenwood and A. M. Gleason, Combinatorial relations and chromatic graphs, Canad. J. Math., 7 (1955), 1-7. H. W. Gould, Letters to N. J. A. Sloane, 1974 EXAMPLE a(2)=6 since in a party with at least 6 people, there are three people mutually acquainted or three people mutually unacquainted. CROSSREFS Cf. A045652. A073591(n) is an upper bound on a(n). Sequence in context: A287901 A143093 A117712 * A106158 A274103 A195995 Adjacent sequences:  A003320 A003321 A003322 * A003324 A003325 A003326 KEYWORD nonn AUTHOR EXTENSIONS Upper bound and additional comments from D. G. Rogers, Aug 27 2006 Better definition from Max Alekseyev, Jan 12 2008 Comment corrected by Brian Kell, Feb 14 2010 Changed a(4) to 62, following Fettes et al. - Jeremy F. Alm, Jun 08 2016 Entry revised by N. J. A. Sloane, Jun 12 2016 STATUS approved

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Last modified February 23 07:24 EST 2020. Contains 332159 sequences. (Running on oeis4.)