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A054922
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Number of connected unlabeled symmetric relations (graphs with loops) having n nodes such that complement is also connected.
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0
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2, 0, 0, 10, 164, 2670, 56724, 1867860, 104538928, 10461483366, 1912179618740, 644464839239880, 402785011941549964, 468944407349226545614, 1021179521951204217530900, 4174755063830188009750183026
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OFFSET
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1,1
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LINKS
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Table of n, a(n) for n=1..16.
V. A. Liskovets, Some easily derivable sequences, J. Integer Sequences, 3 (2000), #00.2.2.
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FORMULA
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2*A054921(n)-A000666(n).
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CROSSREFS
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Sequence in context: A181501 A213704 A000171 * A061848 A193294 A216991
Adjacent sequences: A054919 A054920 A054921 * A054923 A054924 A054925
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KEYWORD
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nonn,easy,changed
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AUTHOR
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N. J. A. Sloane, May 24 2000
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EXTENSIONS
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More terms from Vladeta Jovovic, Jul 17 2000
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STATUS
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approved
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