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A123441 Number of P_4-sparse perfect graphs on n nodes. 0
1, 2, 4, 11, 27, 78, 218, 653, 1963, 6088, 19078, 60825, 195757, 636810, 2087764, 6896119 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
A graph is P_4-sparse if no set of 5 vertices induces a subgraph that contains two or more induced P_4 (path on 4 vertices). P4-sparse graphs are perfect. - Falk Hüffner, Dec 01 2015
REFERENCES
C. T. Hoàng, Perfect graphs, Ph.D. Thesis, School of Computer Science, McGill University, Montreal, Canada, 1985.
LINKS
S. Hougardy, Home Page
S. Hougardy, Classes of perfect graphs, Discr. Math. 306 (2006), 2529-2571.
F. Hüffner, tinygraph, software for generating integer sequences based on graph properties, version 5926e72.
CROSSREFS
Sequence in context: A123440 A071314 A309886 * A086441 A316696 A319616
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Oct 18 2006
EXTENSIONS
a(11)-a(16) added using tinygraph by Falk Hüffner, Jan 16 2016
STATUS
approved

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Last modified April 14 05:31 EDT 2024. Contains 371655 sequences. (Running on oeis4.)