A063851 Triangle T(n,k) (n >= 3, k = 1..n-2) read by rows giving number of nonisomorphic nondegenerate oriented matroids with n points in n-k dimensions.

1, 1, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 1, 11, 11, 1, 1, 1, 135, 2628, 135, 1, 1, 1, 4382, 9276601, 9276601, 4382, 1, 1, 1, 312356

Offset: 3

Author

N. J. A. Sloane, Aug 26 2001

Keywords

• nonn
• tabl
• nice
• more

Examples

			Triangle begins:
1
1,1,
1,1,1,
1,1,1,4,
1,1,1,11,11,
1,1,1,135,2628,135,
1,1,1,4382,9276601,9276601,4382,
1,1,1,312356,...
		

Links

• Lukas Finschi, Homepage of Oriented Matroids [Gives T(9, 5) = T(9, 6) = 9276595.]
• 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.
• 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.
• Komei Fukuda, Hiroyuki Miyata and Sonoko Moriyama, 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 [Beware typos in Table 1.]

Crossrefs

For numbers when degenerate matroids are included see A063804. Two rightmost diagonals are A006248 and A222315. Row sums give A063852.

Extensions

More terms taken from Fukuda et al., 2013. - N. J. A. Sloane, Feb 16 2013