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Search: id:A001927
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| A001927 |
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Number of connected partially ordered sets with n labeled points.
(Formerly M2043 N0809)
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+0
5
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| 1, 1, 2, 12, 146, 3060, 101642, 5106612, 377403266, 40299722580, 6138497261882, 1320327172853172, 397571105288091506, 166330355795371103700, 96036130723851671469482, 76070282980382554147600692, 82226869197428315925408327266
(list; graph; listen)
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OFFSET
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0,3
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REFERENCES
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K. K.-H. Butler and G. Markowsky, Enumeration of finite topologies, Proc. 4th S-E Conf. Combin., Graph Theory, Computing, Congress. Numer. 8 (1973), 169-184.
M. Erne', Struktur- und Anzahlformeln fuer Topologien auf Endlichen Mengen, Manuscripta Math., 11 (1974), 221-259.
M. Erne' and K. Stege, Counting Finite Posets and Topologies, Order, 8 (1991), 247-265.
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LINKS
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Index entries for sequences related to posets
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FORMULA
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E.g.f. A(x)=log(B(x)) where B(x) is e.g.f. of A001035.
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CROSSREFS
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Cf. A000112, A001035, A000608, A066303.
Sequence in context: A035049 A010790 A086928 this_sequence A105558 A126777 A126345
Adjacent sequences: A001924 A001925 A001926 this_sequence A001928 A001929 A001930
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KEYWORD
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nonn,nice,hard
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AUTHOR
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njas
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EXTENSIONS
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More terms from Christian G. Bower (bowerc(AT)usa.net), Dec 12 2001
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