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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

%I

%S 1,1,2,1,3,4,1,4,12,17,1,5,25,206,143,1,6,50,6029,181472,4890,1,7,91,

%T 508321

%N 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.

%D 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.

%D 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

%H L. Finschi, <a href="http://www.om.math.ethz.ch">Homepage of Oriented Matroids</a>

%H L. Finschi and K. Fukuda, <a href="http://www.ifor.math.ethz.ch/staff/finschi/ccgospcaha/ccgospcaha.pdf">Complete combinatorial generation of small point set configurations and hyperplane arrangements</a>, pp. 97-100 in Abstracts 13th Canadian Conference on Computational Geometry (CCCG '01), Waterloo, Aug. 13-15, 2001.

%e Triangle begins:

%e 1

%e 1 2

%e 1 3 4

%e 1 4 12 17

%e 1 5 25 206 143

%e 1 6 50 6029 181472 4890

%e 1 7 91 508321 unknown unknown 461053

%e ...

%Y Diagonals give A063800-A063803, A246988, A246989. Row sums give A063805. For nondegenerate matroids see A063851.

%K nonn,tabl,nice,more

%O 3,3

%A _N. J. A. Sloane_, Aug 20 2001

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Last modified April 23 06:08 EDT 2019. Contains 322381 sequences. (Running on oeis4.)