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A187927 Number of embeddings on the sphere of 2-connected planar graphs, minimum vertex degree 3, with n nodes. 1
2, 13, 163, 2067, 30953, 486674, 7957459, 133344454, 2280001754, 39648557743, 699731146514, 12511186297320 (list; graph; refs; listen; history; text; internal format)
OFFSET

6,1

COMMENTS

The graphs are exactly 2-connected, not at least 2-connected.  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

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Last modified June 28 23:37 EDT 2017. Contains 288851 sequences.