This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A063804 #21 Feb 22 2023 12:00:33 %S A063804 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 A063804 508321 %N 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. %D A063804 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 A063804 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 A063804 Lukas Finschi, <a href="https://finschi.com/math/om/">Homepage of Oriented Matroids</a> %H A063804 L. Finschi and K. Fukuda, <a href="http://www.cccg.ca/proceedings/2001/finschi-1053.ps.gz">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 A063804 Triangle begins: %e A063804 1 %e A063804 1 2 %e A063804 1 3 4 %e A063804 1 4 12 17 %e A063804 1 5 25 206 143 %e A063804 1 6 50 6029 181472 4890 %e A063804 1 7 91 508321 unknown unknown 461053 %e A063804 ... %Y A063804 Diagonals give A063800-A063803, A246988, A246989. Row sums give A063805. For nondegenerate matroids see A063851. %K A063804 nonn,tabl,nice,more %O A063804 3,3 %A A063804 _N. J. A. Sloane_, Aug 20 2001