A132043 - OEIS

A132043

Number of bitransversal (transversal and dual transversal) matroids on n unlabeled elements.

2, 4, 8, 17, 38, 95, 268, 917, 4086

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OFFSET

1,1

COMMENTS

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.

REFERENCES

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

LINKS

Table of n, a(n) for n=1..9.

CROSSREFS

Cf. A049312.

Sequence in context: A118928 A325921 A049312 * A055545 A241671 A368095

Adjacent sequences: A132040 A132041 A132042 * A132044 A132045 A132046

KEYWORD

nonn

AUTHOR

Gordon F. Royle, Oct 30 2007

STATUS

approved