You may find
this problem similar.
In a cube of side 4, I pack eight spheres of unit radius.
What is the largest sphere I can place in the center (such that it doesn't overlap any of the other spheres)?
(In reply to
another dimension by pleasance)
Actually, it goes to infinity with √n.
The answer is actually, √n-1.
But, we're just talking.... It is a very interesting and related problem to PROVE that this is so. Anyone? ;-)