Pascal's Triangle

In a Pascal's Triangle, numbers are arranged starting with a 1 on top of the triangle. Lines underneath are arranged such that every number is the sum of the two numbers above it. So the second line will consist of two 1s, followed by 1,2,1, followed by 1,3,3,3,1, etc
See Also: http://en.wikipedia.org/wiki/Pascal%27s_triangle

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