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A180500
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Triangle read by row. T(n,m) gives the number of isomorphism classes of simple arrangements of n pseudolines and m double pseudolines in the projective plane.
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2
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1, 1, 1, 1, 1, 1, 1, 2, 4, 13, 1, 5, 48, 626, 6570, 1, 25, 1329, 86715, 4822394, 181403533
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OFFSET
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0,8
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REFERENCES
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J. Ferté, V. Pilaud and M. Pocchiola, On the number of arrangements of five double pseudolines, Abstracts 18th Fall Workshop on Comput. Geom. (FWCG08), Troy, NY, October 2008.
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LINKS
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Table of n, a(n) for n=0..20.
J. Ferté, V. Pilaud and M. Pocchiola, On the number of simple arrangements of five double pseudolines, arXiv:1009.1575 [cs.CG], 2010; Discrete Comput. Geom. 45 (2011), 279-302.
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CROSSREFS
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See A180501 for isomorphism classes of all (not only simple) arrangements of n pseudolines and m double pseudolines in the projective plane.
See A180503 for isomorphism classes of simple arrangements of n pseudolines and m double pseudolines in the Moebius strip.
First diagonal gives A006248.
Sequence in context: A059085 A030064 A224886 * A176990 A109928 A023640
Adjacent sequences: A180497 A180498 A180499 * A180501 A180502 A180503
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KEYWORD
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nonn,tabl,more
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AUTHOR
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Vincent Pilaud, Sep 08 2010
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STATUS
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approved
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