Duplicate hunting

[Don Reble]

    I'm interested in the triplicate A051913, A066962, A067020.
    (See also A125866.)
    Can someone please explain what "constructed using conics" means?
-- 
Don Reble  djr at nk.ca


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http://www.research.att.com/~njas/sequences/A126750
http://www.research.att.com/~njas/sequences/A126755

are "biconnected graphs on n nodes with chromatic number 2"

and

"biconnected triangle-free graphs on n nodes with chromatic number 2"



Therefore they are necessarily duplicates seeing chromatic number 2  
forces triangle-free...





--
Associate Professor Gordon Royle
Department of Computer Science & Software Engineering
University of Western Australia
http://people.csse.uwa.edu.au/gordon