%I #3 Mar 31 2012 14:47:13
%N Number of bitransversal (transversal and dual transversal) matroids on n unlabeled elements.
%C A transversal matroid is a matroid whose independent sets are the partial transversals of a family of subsets of [1..n], while a bitransversal matroid is a transversal matroid whose dual is transversal. The principal (or fundamental) transversal matroids enumerated by A049312 form an important subset of bitransversal matroids.
%D Jensen, P. M., Binary fundamental matroids. Algebraic methods in graph theory, Vol. I, II (Szeged, 1978), pp. 281-296, Colloq. Math. Soc. Janos Bolyai, 25, North-Holland, Amsterdam-New York, 1981
%Y Cf. A049312.
%A _Gordon F. Royle_, Oct 30 2007