A058717 Triangle T(n,k) giving number of nonisomorphic loopless matroids of rank k on n labeled points (n >= 1, 1<=k<=n).

1, 1, 1, 1, 2, 1, 1, 4, 3, 1, 1, 6, 9, 4, 1, 1, 10, 25, 18, 5, 1, 1, 14, 70, 85, 31, 6, 1, 1, 21, 217, 832, 288, 51, 7, 1

Offset: 1

Author

N. J. A. Sloane, Dec 31 2000

Keywords

• nonn
• tabl
• nice

Examples

			1;
1,  1;
1,  2,   1;
1,  4,   3,   1;
1,  6,   9,   4,   1;
1, 10,  25,  18,   5,  1;
1, 14,  70,  85,  31,  6, 1;
1, 21, 217, 832, 288, 51, 7, 1;
...
		

Links

• 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

Crossrefs

Cf. A058716 (same except for border), A058710, A058711.

Row sums give A058718. Diagonals give A000065, A058719.

Extensions

Corrected and extended by Jean-François Alcover, Oct 21 2013

Reverted to original data by Jean-François Alcover, Aug 17 2022