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A046910
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Number of connected irreducible quasiorders with n labeled points.
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1
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1, 1, 1, 1, 25, 1321, 70201, 4542721, 384969649, 44087846545, 6926924885881, 1503058888234201, 451117640363382697, 186980881340749198561, 106678398214255092939169, 83440038893764124092029601, 89093417035281194970121062073, 129323858612953057624127147727913, 254190262374139251098507525465587609
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OFFSET
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0,5
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LINKS
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FORMULA
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E.g.f.: 1 + log(A(x) - A(x)*(1 - 1/A(x))^2 where A(x) is the e.g.f. for A000798.
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MATHEMATICA
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nn = 18; A[x_] :=Total[Cases[Import["https://oeis.org/A000798/b000798.txt",
"Table"], {_, _}][[All, 2]]*Table[x^(i - 1)/(i - 1)!, {i, 1, 19}]];
Range[0, nn]! CoefficientList[Series[1 + Log[A[x]] - A[x] (1 - 1/A[x])^2, {x, 0, nn}], x] (* Geoffrey Critzer, Jul 10 2022 *)
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CROSSREFS
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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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STATUS
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approved
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