Infinite Series without an "x" term What are the uses of an infinite series which does not include an "x" variable? If you are looking at an infinite series which sums terms based entirely upon each term's position in the series, or, a series which includes only the variable "n," how would that series be useful once evaluated in closed form? Let's say you could evaluate a series, which only included "n," to the closed form of a trigonometric function. Would that be realistic since, the function would potentially have to be applied only to an "x" value of 1? Or, where in physics would one need a purely numerical summation? Thank you, sincerely.