You are standing in the very corner of a 10 X 10 grid of dots. How many different ways are there to get to the opposite corner of the grid? You must travel through every node once, and only once. You cannot travel diagonally, and you may not go outside of the overall perimeter.

As others have noted the even cases have no possibilities.  Among the odds,

1x1 has 1 solution 
3x3 has 2 solutions
5x5 has 102 solutions (assuming I made no errors)

Now to go see if this is in the OEIS

Posted by Jer on 2005-04-07 18:09:42