I still don't understand the point of the page, but you're right that (1/2)! can be expressed in terms of the gamma function: (1/2)! = Γ(3/2) = √π/2. As usual,

I still don't understand the point of the page, but you're right that (1/2)! can be expressed in terms of the gamma function: (1/2)! = Γ(3/2) = √π/2. As usual, Wolfram Alpha knows all: http://www.wolframalpha.com/input/?i=%281%2F2%29%21 http://www.wolframalpha.com/input/?i=%281%2F2%29%21