A003094: Connected planar graphs with n nodes

[Eric W. Weisstein]

ID Number: A003094 (Formerly M1652)
Sequence:  1,1,1,2,6,20,99,646,5974,71885,1052805,17449299
                        ^^
Name:      Connected planar graphs with n nodes.
References R. J. Wilson, Introduction to Graph Theory. Academic Press, NY,
           1972, p. 162.
           P. Steinbach, Field Guide to Simple Graphs. Design Lab,
           Albuquerque NM, 1990.
Keywords:  nonn,nice,hard
Offset:    0
Author(s): njas
Extension: More terms from Brendan McKay (bdm at cs.anu.edu.au)

I get a(6)=100 instead of a(6)=99 when I compute the above sequence.

Since my counts agree for planar and connected graphs separately

A005470 1,2,4,11,33,142  Planar graphs with n nodes
A001349 1,1,2,6,21,112   Connected graphs with n nodes

I am puzzled that I disagree on the intersection of these two, getting 1 1
2 6 20 100 instead of 1 1 2 6 20 99.  And none of my 100 seems to want to
be isomorphic to any of the others :(

Unfortunately, my code is not sophisticated enough to easily go to higher
#s of nodes.  In any case, can someone double-check the count of planar
connected graphs on 6 nodes?  It is definitely given as 99 in Steinbach,
p. 131, but I don't know what Wilson's book has to say about it.

Cheers,
-Eric

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* Eric W. Weisstein                                                *
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