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Search: id:A004122
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| A004122 |
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Generalized weak orders on n points.
(Formerly M2064)
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+0
4
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| 2, 13, 123, 1546, 24283, 457699, 10064848, 252945467, 7151532895, 224661610888, 7763387794649, 292659248485051, 11951855446598278, 525645673381008537, 24769319755329986599, 1244984053628241578058, 66487872534167725541751
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, John Wiley and Sons, N.Y., 1983.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
C. G. Wagner, Enumeration of generalized weak orders. Arch. Math. (Basel) 39 (1982), no. 2, 147-152.
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..100
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FORMULA
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E.g.f. : 1/(2-exp(x)*exp(exp(x)-1)).
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CROSSREFS
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Cf. A004121, A004123, A000670.
Sequence in context: A127891 A110369 A000180 this_sequence A086630 A151361 A073559
Adjacent sequences: A004119 A004120 A004121 this_sequence A004123 A004124 A004125
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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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Formula and more terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Mar 27 2001
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