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A098851
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Number of triangle-free configurations of type (n_3).
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3
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 4, 14, 162, 4713, 157211
(list;
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listen;
history;
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internal format)
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OFFSET
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1,18
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LINKS
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Table of n, a(n) for n=1..22.
A. Alazemi and A. Betten, Classification of Triangle-Free 22_3 Configurations, International Journal of Combinatorics, Volume 2010, Article ID 767361.
A. Betten, G. Brinkmann and T. Pisanski, Counting symmetric configurations v_3, Discrete Appl. Math., 99 (2000), 331-338.
M. Boben et al., Small triangle-free configurations of points and lines, Discrete Comput. Geom., 35 (2006), 405-427.
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CROSSREFS
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Cf. A001403.
Sequence in context: A162077 A247526 A111266 * A080986 A132555 A129220
Adjacent sequences: A098848 A098849 A098850 * A098852 A098853 A098854
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KEYWORD
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nonn,more,hard
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AUTHOR
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N. J. A. Sloane
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EXTENSIONS
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a(22) from Abdullah Alazemi, Sep 05 2021
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STATUS
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approved
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