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A093351
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Number of labeled n-vertex graphs with a 2-component.
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3
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0, 0, 1, 3, 9, 65, 885, 20769, 904799, 75119535, 12059144775, 3777502008115, 2321770382163177, 2810098818045932049, 6714509196242295683053, 31734155232117923771498025, 297105206555826680431032956415
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,4
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LINKS
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FORMULA
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E.g.f.: (1-exp(-x^2/2))*Sum(2^binomial(n, 2)*x^n/n!, n=0..infinity).
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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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