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A058669 Triangle T(n,k) read by rows, giving number of matroids of rank k on n labeled points (n >= 0, 0<=k<=n). 5
1, 1, 1, 1, 3, 1, 1, 7, 7, 1, 1, 15, 36, 15, 1, 1, 31, 171, 171, 31, 1, 1, 63, 813, 2053, 813, 63, 1, 1, 127, 4012, 33442, 33442, 4012, 127, 1, 1, 255, 20891, 1022217, 8520812, 1022217, 20891, 255, 1, 1, 511 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,5

LINKS

Table of n, a(n) for n=0..46.

W. M. B. Dukes, Tables of matroids

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

Index entries for sequences related to matroids

W. M. B. Dukes, On the number of matroids on a finite set

EXAMPLE

1; 1,1; 1,3,1; 1,7,7,1; ...

CROSSREFS

Row sums give A058673. Diagonals give A058681, A058687. Cf. A053534.

Sequence in context: A184173 A022166 A141689 * A057004 A059328 A174387

Adjacent sequences:  A058666 A058667 A058668 * A058670 A058671 A058672

KEYWORD

nonn,nice,tabl,more

AUTHOR

N. J. A. Sloane, Dec 30 2000

STATUS

approved

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Last modified January 18 04:47 EST 2019. Contains 319269 sequences. (Running on oeis4.)