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A054952
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Number of unlabeled semi-strong digraphs on n nodes with pairwise different components.
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4
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1, 1, 6, 88, 5136, 1052154, 706474926, 1581054875274, 12140605885784816, 328173091958855376334, 31831409045512513121561226, 11234306828778006073392046869300, 14576263867446651299709243211339018934, 70075728362101598938266196294267261948879446
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listen;
history;
text;
internal format)
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OFFSET
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1,3
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COMMENTS
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A digraph is semi-strong if all its weakly connected components are strongly connected. - Andrew Howroyd, Jan 14 2022
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LINKS
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FORMULA
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MATHEMATICA
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m = 15;
A035512 = Cases[Import["https://oeis.org/A035512/b035512.txt", "Table"], {_, _}][[All, 2]];
gf = -1 + Product[(1 + x^n)^A035512[[n + 1]], {n, 1, m}];
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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