

A180500


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.


2



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

0,8


REFERENCES

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.


LINKS

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), 279302.


CROSSREFS

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


KEYWORD

nonn,tabl,more


AUTHOR

Vincent Pilaud, Sep 08 2010


STATUS

approved



