%I A006671 M2269
%S A006671 3,3,3,3,4,4,5,5,5,5,5,5,5,6,6,6,7,7,7
%N A006671 Chromatic number of cycle with n nodes.
%C A006671 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 S. Plouffe in his 1992 dissertation is wrong.
%D A006671 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A006671 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.
%H A006671 S. Plouffe, <a href="http://www.lacim.uqam.ca/%7Eplouffe/articles/MasterThesis.pdf">
               Approximations de S\'{e}ries G\'{e}n\'{e}ratrices et Quelques Conjectures</
               a>, Dissertation, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 
               1992.
%H A006671 S. Plouffe, <a href="http://www.lacim.uqam.ca/%7Eplouffe/articles/FonctionsGeneratrices.pdf">
               1031 Generating Functions and Conjectures</a>, Universit\'{e} du 
               Qu\'{e}bec \`{a} Montr\'{e}al, 1992.
%Y A006671 Sequence in context: A048181 A091799 A035936 this_sequence A046074 A068048 
               A056206
%Y A006671 Adjacent sequences: A006668 A006669 A006670 this_sequence A006672 A006673 
               A006674
%K A006671 nonn
%O A006671 3,1
%A A006671 N. J. A. Sloane (njas(AT)research.att.com).