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A053517
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Number of connected directed 2-multigraphs on n nodes.
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1
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1, 5, 132, 22662, 29174514, 286151774704, 21712410740238954, 12980058344488389640470, 62082372574276838787463958455, 2405193558246444686967534052419452898, 762399004073792344564641131264446658930745417
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OFFSET
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1,2
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COMMENTS
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A 2-multigraph is similar to an ordinary graph except there are 0, 1 or 2 edges between any two nodes (self-loops are not allowed).
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LINKS
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FORMULA
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Inverse Euler transform of A053467.
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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