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Search: id:A006541
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| A006541 |
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Number of dissimilarity relations on an n-set.
(Formerly M4920)
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+0
2
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| 1, 1, 13, 4683, 102247563, 230283190977853, 81124824998504073881821, 6297562064950066033518373935334635, 144199280951655469628360978109406917583513090155
(list; graph; listen)
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OFFSET
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1,3
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
M. Schader, Hierarchical analysis: classification with ordinal object dissimilarities, Metrika, 27 (1980), 127-132.
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FORMULA
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Sum_{i=0..m-1} (m-i)!*Stirling2(m, m-i), where m = n(n-1)/2.
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CROSSREFS
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Cf. A005121.
A000670(n(n-1)/2).
Sequence in context: A094316 A057842 A023345 this_sequence A103857 A032463 A060887
Adjacent sequences: A006538 A006539 A006540 this_sequence A006542 A006543 A006544
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KEYWORD
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nonn,nice,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jan 19 2000
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