[seqfan] Re: Counting multigraphs

Richard Guy rkg at cpsc.ucalgary.ca
Tue Jun 21 01:03:20 CEST 2011


Presumably 1111, 111, 121, 12, 11, 2 and 22.   R.

On Mon, 20 Jun 2011, franktaw at netscape.net wrote:

> I don't understand A007717. I only count 5 multigraphs with 2 edges, not 7: 2 
> connected and 3 disconnected. The link in the sequence didn't get me to 
> anything useful.
>
> Franklin T. Adams-Watters
>
> -----Original Message-----
> From: Charles Greathouse <charles.greathouse at case.edu>
>
> A sequence defined in terms of A007717 was recently submitted, and an
> editor asked if it and A007717 could be extended.  A007717 itself is
> marked as an easy sequence, but I must admit that I'm not sure how to
> extend it.  If it is easy, would someone add a program and more terms
> (ideally a 10,000-term b-file, but the standard three lines would do
> as well)?  I assume this is one of the things that is "well-known to
> those who well-know it".
>
> On the other hand, if it's not easy the keyword, at least, should be
> removed (and whatever can be added should be).
>
> Charles Greathouse
> Analyst/Programmer
> Case Western Reserve University
>
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>



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