Presentation with sequence KOBON TRIANGLES PROBLEM

[Alexandre Wajnberg]

> De : "N. J. A. Sloane" <njas at research.att.com>
> Objet : Re:  Re : Presentation with sequence KOBON TRIANGLES PROBLEM
> 
> Alexandre,  This is in response to your posting of Nov 20 2005.
> You gave a picture showing that a(10) >= 25.
> (I am adding it to the entry for A006066)
> 
> My question is, is it known that a(10) = 26 is impossible?


Not to my (weak) knowledge.

But A006066(6)=7 and a(8)=15 (n even)
are also one unit below their respective upper bound,
and I don't know if it has been proved that
a(6)=8 and a(8)=16 are impossible.

So if a seqfan finds an a(10)=26 construction...
And an a(6)=8 and an a(8)=16...


Alexandre

Note: for n=6 and 8, n(n-2)/3 is integer; for n=4 and 10, not.