[r-t] Crambo - mystery solved(?)

[Robert Johnson]

Thanks for that Richard. I agree with you that the crambo theorem looks like a 
5-bell fluke and that degree 0 changes are likely to kill you on higher 
numbers.

Here's a funny little question vaguely inspired by crambo (tho' crambo doesn't 
actually have this property). Can you constuct an extent on n which remains a 
legal touch if you strike out any row. More generally what is the largest 
k(n) for which  there exists an extent on n which remains a legal touch if 
you strike out any k consecutive rows. (The fact that you can't have more 
than 2^{n/2} rows with any two differing by a legal change (proof an exercise 
to the reader) shows that k=2^{n/2} - 1 is an upper bound for k.)

Robert