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

3,10

Links

Table of n, a(n) for n=3..34.

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.]

Example

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,...

Crossrefs

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

Sequence in context: A113196 A037291 A222317 * A124777 A352834 A203639

Adjacent sequences: A063848 A063849 A063850 * A063852 A063853 A063854

Keyword

nonn,tabl,nice,more

Author

N. J. A. Sloane, Aug 26 2001

Extensions

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

Status

approved