[seqfan] Re: Integral sets of points (A007285, A096872 and A096873)

israel at math.ubc.ca israel at math.ubc.ca
Thu Nov 17 06:21:32 CET 2011


For A007285, you can't have 1 or 2 points "not all on a line", so I don't 
think there should be a(1) or a(2)..

Robert Israel                            israel at math.ubc.ca
Department of Mathematics    http://www.math.ubc.ca/~israel
University of British Columbia        Vancouver, BC, Canada

On Nov 16 2011, Benoît Jubin wrote:

>Dear Seqfans,
>
>I think a few initial values should be added/corrected in the
>sequences A007285, A096872 and A096873, and that the definitions could
>be modified to treat them in a uniform way.  I propose the following;
>can you confirm this is correct?
>
>A007285: Minimum diameter of an integral set of n points in the plane,
>not all on a line.
>add: a(1)=0 and a(2)=1 (therefore modify offset to 1)
>
>A096872: Minimum diameter of an integral set of n points in the plane,
>no 3 on a line.
>modify: a(1)=0
>
>A096873: Minimum diameter of an integral set of n points in the plane,
>no 3 on a line, no 4 on a circle.
>modify: a(1)=0
>add comment: As of 2011, it is not known if this sequence is finite.
>
> For all three sequences: add the definition: "An integral set is a set 
> where all distances between points are integers." add the link: 
> http://ginger.indstate.edu/ge/COMBIN/GEOMETRY/intdistance.html
>
>Add three analog sequences where all points are furthermore required
>to have integral coordinates?
>
>Thanks,
>Benoit
>
>_______________________________________________
>
>Seqfan Mailing list - http://list.seqfan.eu/
>



More information about the SeqFan mailing list