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A098702
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Number of self-polar configurations of type (n_3).
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4
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0, 0, 0, 0, 0, 0, 1, 1, 3, 10, 25, 95, 365, 1432, 5799, 24092, 102413, 445363, 1991320
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,9
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REFERENCES
| 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.
Pisanski, T.; Boben, M.; Marusic, D.; Orbanic, A.; and Graovac, A. The 10-cages and derived configurations. Discrete Math. 275 (2004), 265-276.
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EXAMPLE
| Example: the Fano plane is the only 7_3 configuration and it is self-polar.
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CROSSREFS
| Cf. A001403, A023994.
Sequence in context: A196984 A131433 A110713 * A100001 A190529 A110158
Adjacent sequences: A098699 A098700 A098701 * A098703 A098704 A098705
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KEYWORD
| nonn,nice,hard
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Nov 05 2004
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EXTENSIONS
| a(1)-a(18) from the Betten, Brinkmann and Pisanski article.
a(19) from the Pisanski et al. article.
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