[seqfan] Re: A graph counting problem

[Andrew Weimholt]

On Wed, Dec 30, 2009 at 1:37 PM, Andrew Weimholt
<andrew.weimholt at gmail.com> wrote:
> On Wed, Dec 30, 2009 at 7:20 AM,  <franktaw at netscape.net> wrote:
>>
>> the number of connected graphs of this sort, starting at n = 1,
>>
>> 1,1,2,3,6,12,28,65.
>>
>
> computing by hand I get
>
> 1,1,2,3,6,12,28,65,172, which differs from A073431
>

My program gives

1,1,2,3,6,12,28,65,173   (last term was off by one)

I had all the graphs in my hand computation but miscounted

I can adapt my program to get a few more terms by taking advantage of
the restriction
that nodes with the same label cannot be connected. This will allow me
to use a less
brute-force approach to counting the graphs, particularly for sets of
labels with a high
number of repeats.

Andrew