%I #31 Mar 31 2023 10:00:45
%S 1,5,23,108,940,190214,4886380924
%N Number of nonisomorphic matroids of rank 4 on n labeled points.
%H W. M. B. Dukes, <a href="http://www.stp.dias.ie/~dukes/matroid.html">Tables of matroids</a>.
%H W. M. B. Dukes, <a href="https://web.archive.org/web/20030208144026/http://www.stp.dias.ie/~dukes/phd.html">Counting and Probability in Matroid Theory</a>, Ph.D. Thesis, Trinity College, Dublin, 2000.
%H W. M. B. Dukes, <a href="https://arxiv.org/abs/math/0411557">The number of matroids on a finite set</a>, arXiv:math/0411557 [math.CO], 2004.
%H W. M. B. Dukes, <a href="https://www.emis.de/journals/SLC/wpapers/s51dukes.html">On the number of matroids on a finite set</a>, Séminaire Lotharingien de Combinatoire 51 (2004), Article B51g.
%H Markus Kirchweger, Manfred Scheucher, and Stefan Szeider, <a href="https://doi.org/10.4230/LIPIcs.SAT.2022.4">A SAT Attack on Rota's Basis Conjecture</a>, Leibniz International Proceedings in Informatics (LIPIcs 2022) Vol. 236, 4:1-4:18.
%H Yoshitake Matsumoto, <a href="https://www-imai.is.s.u-tokyo.ac.jp/~ymatsu/matroid/">Database of Matroids</a>
%Y Column k=4 of A053534.
%Y Cf. A058693.
%K nonn,more
%O 4,2
%A _Manfred Scheucher_, Aug 31 2020
%E a(10) from Database of Matroids added by _Andrey Zabolotskiy_, Mar 26 2023