Hi guys, just wondering if you can give me some advice on how to write certain co-efficients with in a compact elegant way. The co-efficients are given by the following rule: a0=1 a1=z a2=z(z-1) a3=z(z-1)(z-2) . . . an=z(z-1)(z-2)...(z-(n-1)) where a = any real number I was thinking of using the following definition, an = z!/(z-n)! which seems to give me the correct results but im worried about whether or not the ! can be defined on real numbers. Like is there a problem with this definition?