I'm not sure if this is a "general" math question but I do think it is an interesting one. The Gamma Function, [itex]\Gamma(t)[/itex], has many interesting definitions. It can take on the form of an integral to an infinite product. There is one particular definition, however, that I am trying to understand that doesn't make sense to me. Take a look at the following link: http://en.wikipedia.org/wiki/Gamma_function#Alternative_definitions The definition for Gamma that confuses me is the one that mentions generalized Laguerre polynomials on that page. We can see that Gamma is a function of 't' and that 'n' is part of the summation. My question is this, what is x suppose to be? What defines it? To me, x appears to be there for no reason. I hope I am just overlooking something simple and someone can point it out to me. Thanks!