[seqfan] Re: median graphs

[Brendan McKay]

Thanks, I submitted a title change for A054927.

Brendan.

On 15/4/19 12:17 pm, israel at math.ubc.ca wrote:
> Yes, it seems to be a different definition.  Page 2 of the Liskovetz
> link in A054927 says:
>
>  median graphs, i.e. (n,N)-graphs with N=\lceil n(n−1)/4 \rceil edges
>
> while I presume A292623 is using the more usual definition of median 
> graphs
> (as in e.g. Wikipedia).
>
> Cheers,
> Robert
>
> On Apr 14 2019, Brendan McKay wrote:
>
>> A054927<http://oeis.org/A054927> is 'Number of connected unlabeled 
>> "median" graphs having n nodes such that complement is also connected.'
>>
>> A292623<http://oeis.org/A292623> is 'Number of median graphs on n 
>> nodes.'
>>
>> Since median graphs are necessarily connected, it seems like A054927 
>> counts a subset of A292623. But the numbers in A054927 for large n 
>> are bigger.
>>
>> What's going on?  Two different definitions of "median"?
>>
>> Brendan.
>>
>>
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>>
>
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