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A005806
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Number of comparative probability orderings on n elements.
(Formerly M2072)
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2
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OFFSET
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0,4
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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).
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LINKS
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FORMULA
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EXAMPLE
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For n = 3, the two orders are 1 < 2 < 12 < 3 < 13 < 23 < 123 and 1 < 2 < 3 < 12 < 13 < 23 < 123.
For zero elements, there is exactly one ordering. - M. F. Hasler, Mar 17 2023
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CROSSREFS
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KEYWORD
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nonn,nice,hard,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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