Factorial y Número Combinatorio

$$n! =1x2x3x4x \cdot \cdot \cdot x(n-1)xn; n \in N; n>1$$

$$1! = 1$$

$$0! = 1$$

$$C{^n_k} = ({^n_k}) = \frac{n!}{(n-k)!k!}$$

$$C{^n_0} = 1$$

$$C{^n_1} = n$$

$$C{^n_n} = 1$$