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A018242
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Number of projective order types; number of simple arrangements of n lines.
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2
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1, 1, 1, 1, 1, 1, 4, 11, 135, 4381, 312114, 41693377
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,7
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REFERENCES
| J. E. Goodman and J. O'Rourke, editors, Handbook of Discrete and Computational Geometry, CRC Press, 1997, p. 102.
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CROSSREFS
| Cf. A006247, A006248, A063666.
Sequence in context: A125888 A167418 A055979 * A006248 A119571 A089920
Adjacent sequences: A018239 A018240 A018241 * A018243 A018244 A018245
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| a(11) from Franz Aurenhammer (auren(AT)igi.tu-graz.ac.at), Feb 05, 2002
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