Pascal's triangle

This is formed by putting a 1 at the top.

Then at the next level the number is the sum of the two numbers above and to the left and right.

This very simple recipe generates the combinatorial co-efficients, and also the binomial co-efficients.

It starts like this:

			1
		1		1
	1		2		1
1		3		3		1
1	4		6		4		1