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Search: id:A058682
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| A058682 |
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p(0)+p(1)+...+p(n-1)-n, where p = partition numbers, A000041. |
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+0
3
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| 0, 0, 1, 3, 7, 13, 23, 37, 58, 87, 128, 183, 259, 359, 493, 668, 898, 1194, 1578, 2067, 2693, 3484, 4485, 5739, 7313, 9270, 11705, 14714, 18431, 22995, 28598, 35439, 43787, 53929, 66238, 81120, 99096, 120732, 146746, 177930, 215267
(list; graph; listen)
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OFFSET
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0,4
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COMMENT
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Number of non-isomorphic rank-2 matroids over S_n.
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LINKS
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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
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MAPLE
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a:=n->add(numbpart(k)-1, k=1..n-1): seq(a(n), n=1..41); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jun 01 2008
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CROSSREFS
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Cf. A000041, A000070. A diagonal of A053534.
Sequence in context: A075321 A164787 A131205 this_sequence A081995 A053599 A136851
Adjacent sequences: A058679 A058680 A058681 this_sequence A058683 A058684 A058685
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Dec 30 2000
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