[seqfan] A000081 & nonoverlapping circles(?)

[r.shepherd]

Brief update:

My misinterpretation of the comments in A000081 caused
me to rediscover what are apparently called "penny graphs"
according to a professor Jim Nastos contacted.

After time to do other things, Jim and I will add a new
sequence (or update an existing sequence with comments
and references as appropriate).

Currently, it looks like 1,1,2,4,10,25,...
is the sequence for penny graphs (0,1,2,... unit circles with
non-overlapping interiors).
[My previous 9 was in error -- I missed at least 1 -- but
we're fairly sure these are correct now.].

In case anyone wants to look at the situation for five unit
circles (giving 25 penny graphs), you may access my
.jpg which Jim has put at
http://www.cs.ualberta.ca/~nastos/circles25.JPG
(The diagram does not actually picture the associated
graphs at this point.  Also, please ignore the A000081
reference there, which no longer applies.).

If I've missed any in this 5-circle case, please let me know.

Thanks,
Rick