Imagine a 3 dimensional grid with N x N x N points.
Place as many points as possible on this grid, such that there are no 3 points in a line (for N = 2, this is of course 8).
How much is it for N = 3, 4 or 5?

(In reply to re: N=4? probably not by Justin)

This solution does not work.  You have misinterpreted "line" to mean a "row" of three points.  The points do not have to be evenly spaced to all be on the same line. 

The following three points are in a line.

**0*

Posted by Tristan on 2005-05-14 01:47:54