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A000066 Smallest number of vertices in trivalent graph with girth (shortest cycle) = n.
(Formerly M1013 N0380)
8
4, 6, 10, 14, 24, 30, 58, 70, 112, 126 (list; graph; refs; listen; history; internal format)
OFFSET

3,1

COMMENTS

Also called the (3,n) cage graph.

Recently (unpublished) McKay and Myrvold proved that the minimal graph on 112 vertices is unique. - May 20 2003

If there are n vertices and e edges, then 3n=2e, so n is always even.

REFERENCES

A. T. Balaban, Trivalent graphs of girth nine and eleven and relationships among cages, Rev. Roum. Math. Pures et Appl. 18 (1973) 1033-1043.

Brendan McKay, personal communication.

Brendan McKay, W. Myrvold and J. Nadon, Fast backtracking principles applied to find new cages, 9th Annual ACM-SIAM Symposium on Discrete Algorithms, 1998, 188-191.

M. O'Keefe and P. K. Wong, A smallest graph of girth 10 and valency 3, J. Combin. Theory, B 29 (1980), 91-105.

H. Sachs, On regular graphs with given girth, pp. 91-97 of M. Fiedler, editor, Theory of Graphs and Its Applications: Proceedings of the Symposium, Smolenice, Czechoslovakia, 1963. Academic Press, NY, 1964.

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Wong, Pak Ken; Cages-a survey. J. Graph Theory 6 (1982), no. 1, 1-22.

LINKS

Gordon Royle, Cubic Cages

Eric Weisstein's World of Mathematics, Cage Graph

CROSSREFS

Cf. A054760, A006787, A052453 (number of such graphs).

Sequence in context: A141247 A049632 A061227 * A061645 A188592 A188586

Adjacent sequences:  A000063 A000064 A000065 * A000067 A000068 A000069

KEYWORD

nonn,hard,nice,changed

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

EXTENSIONS

Additional comments from Matthew Cook (matthewc(AT)caltech.edu), May 15, 2003

Balaban proved 112 as an upper bound for a(11). The proof that it is also a lower bound is in the paper by Brendan McKay, W. Myrvold and J. Nadon.

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Last modified February 13 21:55 EST 2012. Contains 205561 sequences.