

A187927


Number of embeddings on the sphere of 2connected planar graphs, minimum vertex degree 3, with n nodes.


1



2, 13, 163, 2067, 30953, 486674, 7957459, 133344454, 2280001754, 39648557743, 699731146514, 12511186297320
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OFFSET

6,1


COMMENTS

The graphs are exactly 2connected, not at least 2connected. The graphs were enumerated using plantri (by B.D. McKay & G. Brinkmann) for the purpose of finding compound perfect squared squares.


REFERENCES

S. E. Anderson, Compound Perfect Squared Squares of the Order Twenties, 2013; http://www.squaring.net/downloads/cpss.pdf


LINKS

Table of n, a(n) for n=6..17.
Stuart Anderson, Compound Perfect Squared Squares
B D McKay and G. Brinkmann, Plantri Guide
Gunnar Brinkmann and Brendan McKay, Guide to using plantri [Cached copy, with permission]


PROG

Use ;
plantri p c2 m3 x u v n ; or
plantri pc2m3xuv n
to count the graphs where n is the number of nodes,


CROSSREFS

Cf. A034889, A181340, A187928, A000944.
Sequence in context: A192563 A014507 A132614 * A252766 A098638 A090643
Adjacent sequences: A187924 A187925 A187926 * A187928 A187929 A187930


KEYWORD

nonn,more,hard


AUTHOR

Stuart E Anderson, Mar 16 2011


EXTENSIONS

a(15)a(17) from Lorenz Milla, Oct 08 2013


STATUS

approved



