Project Euler Solution #15 in Javascript
Lattice paths
Starting in the top left corner of a 2×2 grid, and only being able to move to the right and down, there are exactly 6 routes to the bottom right corner.
How many such routes are there through a 20×20 grid?
2x2 = 6 routes
3x3 = 20 routes
4x4 = 70 routes
5x5 = 252 routes
6x6 = 924 routes