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A002501
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7^n-3*4^n+2*3^n.
(Formerly M5078 N2197)
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13
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1, 19, 205, 1795, 14221, 106819, 778765, 5581315, 39606541, 279447619, 1965098125, 13792018435, 96690872461, 677427332419, 4744368982285, 33220131761155, 232579232659981, 1628208214321219, 11398072876175245
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Counts connected relations.
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REFERENCES
| G. Kreweras, Inversion des polynomes de Bell bidimensionnels et application au denombrement des relations binaires connexes. C. R. Acad. Sci. Paris Ser. A-B 268 1969 A577-A579.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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CROSSREFS
| Cf. A005333, A001047, A002502, A093732, A093733.
Sequence in context: A113596 A155670 A085770 * A125407 A023017 A022647
Adjacent sequences: A002498 A002499 A002500 * A002502 A002503 A002504
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KEYWORD
| nonn,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| Better definition and more terms from Goran Kilibarda, Vladeta Jovovic (vladeta(AT)eunet.rs), Apr 14 2004
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