|
| |
|
|
A006671
|
|
Chromatic number of cycle with n nodes.
(Formerly M2269)
|
|
1
|
|
|
|
3, 3, 3, 3, 4, 4, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 7, 7, 7
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
3,1
|
|
|
COMMENTS
|
The g.f. -(-3+3*z**3-z**4-3*z**5-z**6+4*z**7)/(z**6+z**5+z**2+z+1)/(z-1)**2 conjectured by Simon Plouffe in his 1992 dissertation is wrong.
|
|
|
REFERENCES
|
K. Al-Wahabi, R. Bari, F. Harary and D. Ullman, The edge-distinguishing chromatic number of paths and cycles, pp. 17-22 of Graph Theory in Memory of G. A. Dirac (Sandbjerg, 1985). Edited by L. D. Andersen et al., Annals of Discrete Mathematics, 41. North-Holland Publishing Co., Amsterdam-New York, 1989.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
|
|
|
LINKS
|
Table of n, a(n) for n=3..21.
_Simon Plouffe_, Approximations de S\'{e}ries G\'{e}n\'{e}ratrices et Quelques Conjectures, Dissertation, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.
_Simon Plouffe_, 1031 Generating Functions and Conjectures, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.
|
|
|
CROSSREFS
|
Sequence in context: A216194 A179847 A035936 * A046074 A068048 A176994
Adjacent sequences: A006668 A006669 A006670 * A006672 A006673 A006674
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
N. J. A. Sloane.
|
|
|
STATUS
|
approved
|
| |
|
|
