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A018242 Number of projective order types; number of simple arrangements of n lines. 5
1, 1, 1, 1, 1, 1, 4, 11, 135, 4381, 312114, 41693377 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,7

REFERENCES

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

LINKS

Table of n, a(n) for n=0..11.

S. Felsner and J. E. Goodman, Pseudoline Arrangements. In: Toth, O'Rourke, Goodman (eds.) Handbook of Discrete and Computational Geometry, 3rd edn. CRC Press, 2018.

Komei Fukuda, Hiroyuki Miyata, Sonoko Moriyama, Complete Enumeration of Small Realizable Oriented Matroids. Discrete Comput. Geom. 49 (2013), no. 2, 359-381. MR3017917. Also arXiv:1204.0645 [math.CO], 2012. - From N. J. A. Sloane, Feb 16 2013

FORMULA

Asymptotics: a(n) = 2^(Theta(n log n)). This is Bachmann-Landau notation, that is, there are constants n_0, c, and d, such that for every n >= n_0 the inequality 2^(c n log n) <= a(n) <= 2^(d n log n) is satisfied. For more information see e.g. the Handbook of Discrete and Computational Geometry. - Manfred Scheucher, Sep 12 2019

CROSSREFS

Cf. A006247, A006248, A063666. A diagonal of A222317.

Sequence in context: A214113 A167418 A055979 * A006248 A119571 A089920

Adjacent sequences:  A018239 A018240 A018241 * A018243 A018244 A018245

KEYWORD

nonn,more

AUTHOR

N. J. A. Sloane

EXTENSIONS

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

STATUS

approved

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Last modified August 13 11:30 EDT 2022. Contains 356091 sequences. (Running on oeis4.)