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A048872
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Number of non-isomorphic arrangements of n lines in the real projective plane such that the lines do not all pass through a common point.
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7
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OFFSET
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3,2
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REFERENCES
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J. E. Goodman and J. O'Rourke, editors, Handbook of Discrete and Computational Geometry, CRC Press, 1997, p. 102.
B. Grünbaum, Arrangements and Spreads. American Mathematical Society, Providence, RI, 1972, p. 4.
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LINKS
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Stefan Felsner and Jacob E. Goodman, Pseudoline Arrangements, Chapter 5 of Handbook of Discrete and Computational Geometry, CRC Press, 2017, see Table 5.6.1. [Specific reference for this sequence] - N. J. A. Sloane, Nov 14 2023
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CROSSREFS
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See A132346 for the sequence when we include the arrangement where the lines do pass through a common point, which is 1 greater than this.
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KEYWORD
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nonn,nice,more
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AUTHOR
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EXTENSIONS
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a(7)-a(9) from Handbook of Discrete and Computational Geometry, 2017, by Andrey Zabolotskiy, Oct 09 2017
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STATUS
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approved
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