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A054919
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Number of nonisomorphic connected unlabeled binary relations on n nodes.
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1
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2, 7, 86, 2818, 285382, 96324549, 112087100482, 458071928280897, 6665704296529088252, 349377209492194571020053, 66602723163954144515240479674, 46557323273646194397778583902876038
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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LINKS
| V. A. Liskovets, Some easily derivable sequences, J. Integer Sequences, 3 (2000), #00.2.2.
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FORMULA
| EULERi transform of A000595.
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EXAMPLE
| 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
| Sequence in context: A062764 A163855 A041291 * A119157 A079701 A096208
Adjacent sequences: A054916 A054917 A054918 * A054920 A054921 A054922
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), May 24 2000
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EXTENSIONS
| More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Jul 16 2000
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