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Search: id:A054919
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| A054919 |
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Number of nonisomorphic connected unlabeled binary relations on n nodes. |
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+0
2
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| 2, 7, 86, 2818, 285382, 96324549, 112087100482, 458071928280897, 6665704296529088252, 349377209492194571020053, 66602723163954144515240479674, 46557323273646194397778583902876038
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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V. A. Liskovets, Some easily derivable sequences, J. Integer Sequences, 3 (2000), #00.2.2.
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FORMULA
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EULERi transform of A000595.
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EXAMPLE
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Nonisomorphic connected relations on set {1,2} are {2r1}, {1r1,2r1}, {2r1,2r2}, {1r1,2r1,2r2}, {1r2,2r1}, {1r1,1r2,2r1}, {1r1,1r2,2r1,2r2} so a(2)=7.
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CROSSREFS
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Sequence in context: A111822 A062764 A041291 this_sequence A119157 A079701 A096208
Adjacent sequences: A054916 A054917 A054918 this_sequence A054920 A054921 A054922
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KEYWORD
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nonn,easy
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AUTHOR
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njas, May 24 2000
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EXTENSIONS
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More terms from Vladeta Jovovic (vladeta(AT)Eunet.yu), Jul 16 2000
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