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A334303 Numbers m such that the Thue chromatic number of graph C_m is equal to 4. 0
5, 7, 9, 10, 11, 14, 17 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
The Thue chromatic number of a graph G is the least number k such that there is a nonrepetitive coloring of length k, and no such coloring exists of length < k. (A coloring is nonrepetitive iff there is no path of even length such that the colors in the first half are in the same sequence as the colors in the second half.)
The Thue chromatic number of C_m for any other m > 2 is equal to 3.
LINKS
J. D. Currie, There are ternary circular square-free words of length n for n >= 18, Elect. J. Combinatorics 9 (2002), Note #N10, 7 pp.
J. Grytczuk, Nonrepetitive colorings of graphs - a survey, Int. J. Math. Math. Sci. (2007), Art. ID 74639, 10 pp.
EXAMPLE
5 is in the sequence because at least four colors are needed to make an non-repetitive coloring of C_5.
CROSSREFS
Sequence in context: A275718 A129270 A153031 * A184110 A138892 A190202
KEYWORD
nonn,fini,full
AUTHOR
Bartlomiej Pawlik, Apr 22 2020
STATUS
approved

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Last modified March 29 11:14 EDT 2024. Contains 371278 sequences. (Running on oeis4.)