A063854 -id:A063854 - cp's OEIS frontend

A063853 Triangle T(n,k) (n >= 3, k = 1..n-2) read by rows giving number of abstract order types of configurations of n points in n-k dimensions.

1, 1, 3, 1, 5, 11, 1, 8, 55, 93, 1, 11, 204, 5083, 2121, 1, 15, 705, 505336, 10775236, 122508, 1, 19, 2293

Offset: 3

N. J. A. Sloane, Aug 26 2001

			Triangle begins:
  1;
  1,3;
  1,5,11;
  1,8,55,93;
  ...

Lukas Finschi, Homepage of Oriented Matroids
Lukas Finschi, A Graph Theoretical Approach for Reconstruction and Generation of Oriented Matroids, A dissertation submitted to the Swiss Federal Institute of Technology, Zurich for the degree of Doctor of Mathematics, 2001.
Lukas Finschi and K. Fukuda, Complete combinatorial generation of small point set configurations and hyperplane arrangements, pp. 97-100 in Abstracts 13th Canadian Conference on Computational Geometry (CCCG '01), Waterloo, Aug. 13-15, 2001.

Diagonals give A063854, A063855, A063856, A246990, A246991. Row sums give A063857.

A180502 Triangle read by row. T(n,m) gives the number of isomorphism classes of arrangements of n pseudolines and m double pseudolines in the Moebius strip.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 5, 17, 59, 3, 45, 799, 15649, 245351

Offset: 0

Vincent Pilaud, Sep 08 2010

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.

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.

See A180503 for isomorphism classes of simple arrangements of n pseudolines and m double pseudolines in the Moebius strip.
See A180501 for isomorphism classes of arrangements of n pseudolines and m double pseudolines in the projective plane.
First diagonal gives A063854.

cp's OEIS Frontend

A063853 Triangle T(n,k) (n >= 3, k = 1..n-2) read by rows giving number of abstract order types of configurations of n points in n-k dimensions.

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