[seqfan] Re: Number of Euler graphs: A002854 or something else?

[Joerg Arndt]

* N. J. A. Sloane <njas at research.att.com> [Feb 05. 2010 09:06]:
> Brendan said:
> 
> > And OEIS should state the definition being used for A002854.
> 
> It does!  Look:
> 
> %C A002854 A graph is an Euler graph iff every node has even degree.
> It need not be connected. 

Should we add an image for "Euler graph"?

a(4) = 3:

1)
o  o

o  o

2)
o - o

o - o


3)
o - o
|   |
o - o


What are the 2-graphs?


> [...]


Also may make "switching classes" explicit by
mentioning that switching at any node is the
equivalence relation.