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A063804
Triangle T(n,k) (n >= 3, k = 1..n-2) read by rows, giving number of nonisomorphic oriented matroids with n points in n-k dimensions.
8
1, 1, 2, 1, 3, 4, 1, 4, 12, 17, 1, 5, 25, 206, 143, 1, 6, 50, 6029, 181472, 4890, 1, 7, 91, 508321
OFFSET
3,3
REFERENCES
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.
Fukuda, Komei; Miyata, Hiroyuki; Moriyama, Sonoko. Complete Enumeration of Small Realizable Oriented Matroids. Discrete Comput. Geom. 49 (2013), no. 2, 359--381. MR3017917. - From N. J. A. Sloane, Feb 16 2013
LINKS
L. 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.
EXAMPLE
Triangle begins:
1
1 2
1 3 4
1 4 12 17
1 5 25 206 143
1 6 50 6029 181472 4890
1 7 91 508321 unknown unknown 461053
...
CROSSREFS
Diagonals give A063800-A063803, A246988, A246989. Row sums give A063805. For nondegenerate matroids see A063851.
Sequence in context: A327083 A104002 A073135 * A213800 A224823 A372387
KEYWORD
nonn,tabl,nice,more
AUTHOR
N. J. A. Sloane, Aug 20 2001
STATUS
approved