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A067309
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Number of symmetric unlabeled digraphs (unlabeled digraphs with nontrivial automorphism group).
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1
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OFFSET
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0,3
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LINKS
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FORMULA
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EXAMPLE
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For n=4 nodes from the 218 (=A000273(4)) unlabeled nonisomorphic digraphs 136 (=A051504(4)) are asymmetric, so 218 - 136 = 82 are somehow symmetric.
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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