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Search: id:A001929
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| A001929 |
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Number of connected topologies on n labeled points.
(Formerly M3070 N1245)
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3
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| 1, 1, 3, 19, 233, 4851, 158175, 7724333, 550898367, 56536880923, 8267519506789, 1709320029453719, 496139872875425839, 200807248677750187825, 112602879608997769049739, 86955243134629606109442219, 91962123875462441868790125305
(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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FORMULA
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a(n) = Sum_{k=0..n} Stirling2(n,k)*A001927(k). - Vladeta Jovovic (vladeta(AT)Eunet.yu), Apr 10 2006
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CROSSREFS
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Cf. A001928, A001930.
Adjacent sequences: A001926 A001927 A001928 this_sequence A001930 A001931 A001932
Sequence in context: A136504 A003111 A126444 this_sequence A135754 A118023 A054590
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KEYWORD
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nonn,nice
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AUTHOR
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njas
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EXTENSIONS
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More terms from Vladeta Jovovic (vladeta(AT)Eunet.yu), Apr 10 2006
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