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Search: id:A046908
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| A046908 |
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Number of irreducible posets with n labeled points. |
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+0
2
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| 1, 1, 1, 7, 97, 2251, 80821, 4305127, 332273257, 36630174931, 5711638291981, 1249898984911567, 381230073532620577, 161042140788424003291, 93667063572594041040421, 74610767840852891620692727
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OFFSET
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0,4
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REFERENCES
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J. A. Wright, There are 718 6-point topologies, quasi-orderings, and transgraphs, Notices Amer. Math. Soc., 17 (1970), p. 646, Abstract #70T-A106.
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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) = 2-1/B(x), where B(x) is e.g.f. of A001035. - Vladeta Jovovic (vladeta(AT)Eunet.yu), Jan 10 2006
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CROSSREFS
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Cf. A046907.
Sequence in context: A132061 A003710 A027837 this_sequence A005014 A022008 A124092
Adjacent sequences: A046905 A046906 A046907 this_sequence A046909 A046910 A046911
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KEYWORD
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nonn
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AUTHOR
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John A. Wright.
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EXTENSIONS
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More terms from Vladeta Jovovic (vladeta(AT)Eunet.yu), Jan 10 2006
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