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A245731
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Number of connected labeled transitive relations on an n-set.
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2
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1, 2, 9, 109, 2647, 110481, 7291543, 726434549, 106312974249, 22465350835849, 6771847676632679, 2883916106465622053, 1720792953946798909927, 1427968172285571102335605, 1637002867699829205840095585, 2577011453377960519672777065693, 5541005747990556022043234479371823, 16195114271558690956785525865003941945, 64068293759315414337050896928055465961863
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OFFSET
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0,2
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LINKS
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FORMULA
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E.g.f.: log(A(x + exp(x) - 1)) + 1 where A(x) is the e.g.f. for A001035.
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EXAMPLE
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a(2) = 9. There are 13 transitive relations on the set {1,2}. Four of these are not connected: {}, {(1,1)}, {(2,2)}, {(1,1),(2,2)}. 13-4=9.
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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