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A006247 Number of pseudolines with a marked cell. Number of Euclidean pseudo-order types: nondegenerate abstract order types of configurations of n points in the plane.
(Formerly M0917)
3
1, 1, 1, 2, 3, 16, 135, 3315, 158830, 14320182, 2343203071 (list; graph; refs; listen; history; internal format)
OFFSET

1,4

REFERENCES

Aichholzer, F. Aurenhammer and H. Krasser. Enumerating order types for small point sets with applications. In Proc. 17th Ann. ACM Symp. Computational Geometry, pages 11-18, Medford, Massachusetts, USA, 2001. [Computes a(10)]

J. Ferte, V. Pilaud and M. Pocchiola, On the number of simple arrangements of five double pseudolines. Discrete Comput. Geom. 45 (2011), 279-302.

J. E. Goodman and J. O'Rourke, editors, Handbook of Discrete and Computational Geometry, CRC Press, 1997, p. 102.

J. E. Goodman and R. Pollack, Semispaces of configurations, cell complexes of arrangements, J. Combin. Theory, A 37 (1984), 257-293.

D. E. Knuth, ``Axioms and hulls,'' Lect. Notes Comp. Sci., Vol. 606.

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

LINKS

L. Finschi, Homepage of Oriented Matroids

L. Finschi and K. Fukuda, Complete combinatorial generation of small point set configurations and hyperplane arrangements, pp. 97-100 in Abstracts 13-th Canadian Conference on Computational Geometry (CCCG '01), Waterloo, Aug. 13-15, 2001.

CROSSREFS

Cf. A063852, A006248.

Sequence in context: A067848 A139802 A063666 * A052318 A141309 A179442

Adjacent sequences:  A006244 A006245 A006246 * A006248 A006249 A006250

KEYWORD

nonn,nice,hard

AUTHOR

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

EXTENSIONS

a(11) from Franz Aurenhammer (auren(AT)igi.tu-graz.ac.at), Feb 05, 2002

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Last modified February 15 20:26 EST 2012. Contains 205852 sequences.