a sequence that needs extending

[Dean Hickerson]

> If any other properties of these matrices are known, the search could be
> made faster by incorporating more constraints.  For example, is it known
> that every row and column will have some cell occupied, as appears to be
> true from empirical evidence?

As far as I know that hasn't been proved, but I'd be very surprised if it
turned out to be false.

Have you tried dropping the requirement that x(i,j,k) be 0 or 1, and instead
let it be any real number in [0,1]?  That should make the program faster,
right?  I wonder if it gives any useful bounds on a(n).

Dean Hickerson
dean at math.ucdavis.edu