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A006541
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Number of dissimilarity relations on an n-set.
(Formerly M4920)
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2
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OFFSET
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1,3
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REFERENCES
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M. Schader, Hierarchical analysis: classification with ordinal object dissimilarities, Metrika, 27 (1980), 127-132.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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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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MATHEMATICA
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PROG
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CROSSREFS
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KEYWORD
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nonn,nice,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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