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A002773 Number of nonisomorphic simple matroids (or geometries) with n points.
(Formerly M1197 N0462)
7
1, 1, 1, 2, 4, 9, 26, 101, 950, 376467 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

REFERENCES

Bansal, Nikhil, Rudi A. Pendavingh, and Jorn G. van der Pol. "On the number of matroids." Proceedings of the Twenty-Fourth Annual ACM-SIAM Symposium on Discrete Algorithms. SIAM, 2013; full version in Combinatorica, 35:3 (2015), 253-277.

Miklos Bona, editor, Handbook of Enumerative Combinatorics, CRC Press, 2015, page 138.

Crapo, Henry H.; Rota, Gian-Carlo; On the foundations of combinatorial theory. II. Combinatorial geometries. Studies in Appl. Math. 49 1970 109-133.

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Table of n, a(n) for n=0..9.

N. Bansal and R. Pendavingh, On the number of matroids, arXiv:1206.6270v1 [math.CO], Jun 27 2012.

J. E. Blackburn, H. H. Crapo, and D. A. Higgs, A catalogue of combinatorial geometries, Math. Comp 27 1973 155-166.

Crapo, Henry H.; Rota, Gian-Carlo; On the foundations of combinatorial theory. II. Combinatorial geometries, Studies in Appl. Math. 49 1970 109-133. [Annotated scanned copy of pages 126 and 127 only]

W. M. B. Dukes, Tables of matroids

W. M. B. Dukes, Counting and Probability in Matroid Theory, Ph.D. Thesis, Trinity College, Dublin, 2000.

Gordon Royle and Dillon Mayhew, 9-element matroids

N. J. A. Sloane, Initial terms (* denotes 5 points in general position in 4-space)

Eric Weisstein's World of Mathematics, Matroid.

Index entries for sequences related to matroids

CROSSREFS

Cf. A055545, A056642. Row sums of A058730.

Sequence in context: A087378 A004252 A114957 * A112706 A110138 A148085

Adjacent sequences:  A002770 A002771 A002772 * A002774 A002775 A002776

KEYWORD

nonn,nice,more

AUTHOR

N. J. A. Sloane.

EXTENSIONS

a(9) from Gordon Royle, Dec 23 2006

STATUS

approved

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Last modified January 15 19:06 EST 2019. Contains 319171 sequences. (Running on oeis4.)