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A098702 Number of self-polar configurations of type (n_3). 4
0, 0, 0, 0, 0, 0, 1, 1, 3, 10, 25, 95, 365, 1432, 5799, 24092, 102413, 445363, 1991320 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,9

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.

LINKS

Table of n, a(n) for n=1..19.

EXAMPLE

Example: the Fano plane is the only 7_3 configuration and it is self-polar.

CROSSREFS

Cf. A001403, A023994.

Sequence in context: A196984 A131433 A110713 * A100001 A190529 A212967

Adjacent sequences:  A098699 A098700 A098701 * A098703 A098704 A098705

KEYWORD

nonn,nice,hard

AUTHOR

N. J. A. Sloane, Nov 05 2004

EXTENSIONS

a(1)-a(18) from the Betten, Brinkmann and Pisanski article.

a(19) from the Pisanski et al. article.

STATUS

approved

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Last modified May 19 23:29 EDT 2013. Contains 225436 sequences.