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A097875
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Denominator of J(n) = A000356(n)/A000309(n) (average number of 4-colorings of rank 0 in a rooted nonseparable map which is trivalent and has 2n nodes.
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0
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1, 4, 24, 88, 52, 2176, 41344, 55936, 22080, 2561280, 27617280, 16570368, 34061312, 1540980736, 23512383488, 100462002176, 50231001088, 3741530783744, 4029340844032, 5798319751168, 4112761683968, 526433495547904, 12757611732533248, 129398633287122944
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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REFERENCES
| W. T. Tutte, On the enumeration of four-colored maps, SIAM J. Appl. Math., 17 (1969), 454-460.
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EXAMPLE
| 1, 5/4, 35/24, 147/88, 99/52, 4719/2176, 102245/41344, ...
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CROSSREFS
| Cf. A000356, A000309, A097982.
Sequence in context: A069145 A005561 A061612 * A026694 A026967 A026977
Adjacent sequences: A097872 A097873 A097874 * A097876 A097877 A097878
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KEYWORD
| nonn,frac
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Sep 21 2004
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