

A097875


Denominator of J(n) = A000356(n)/A000309(n) (average number of 4colorings of rank 0 in a rooted nonseparable map which is trivalent and has 2n nodes.


0



1, 4, 24, 88, 52, 2176, 41344, 55936, 22080, 2561280, 27617280, 16570368, 34061312, 1540980736, 23512383488, 100462002176, 50231001088, 3741530783744, 4029340844032, 5798319751168, 4112761683968, 526433495547904, 12757611732533248, 129398633287122944
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OFFSET

1,2


REFERENCES

W. T. Tutte, On the enumeration of fourcolored maps, SIAM J. Appl. Math., 17 (1969), 454460.


LINKS

Table of n, a(n) for n=1..24.


EXAMPLE

1, 5/4, 35/24, 147/88, 99/52, 4719/2176, 102245/41344, ...


CROSSREFS

Cf. A000356, A000309, A097982.
Sequence in context: A210569 A005561 A061612 * A212681 A026694 A026967
Adjacent sequences: A097872 A097873 A097874 * A097876 A097877 A097878


KEYWORD

nonn,frac


AUTHOR

N. J. A. Sloane, Sep 21 2004


STATUS

approved



