what sequences most need extending?

[Rainer Rosenthal]

> Dear Seqfans,  I got email asking me to propose
> a sequence that a group of programmers could
> work on as a challenge.  The following
> constraints were suggested:
> 
> 1) It must be NP-complete
> 2) It must be simple to describe
> 3) It should not have been widely explored
> 4) A solution must be easy to check (= it doesn't 
>    require a lot of computation)
> 5) It has to be computed from N=8 to at most 64
> 
> Does anyone have a good suggestion?
> 

Dear Neil,

well indeed, I do have such a suggestion. In the german 
newsgroup de.sci.mathematik we did discuss "Perfect Rulers" 
and there were some enhancements for 
http://www.research.att.com/projects/OEIS?Anum=A004137
some weeks ago.

Let them compute A004137(n) from scratch. They will
enjoy (I hope). And the OEIS will be glad :-)

Best regards,
Rainer Rosenthal
r.rosenthal at web.de