Whilst i understand what you're trying to do Khandro, I'm afraid what you're seeking cannot possibly exist.
Chemical formulae in simple terms show the elemental composition of a substance. Whilst straightforward paper is predominantly made of cellulose, it is incorrect to provide a general formula for cellulose as the same general formula applies to hundreds and sometimes thousands of other compounds. This is easily demonstrated by substituting numbers instead of "n" in the examples given elsewhere on this thread and looking up the result. Now that's out of the way, let's go on.
I won't discuss inductively coupled plasma mass spectrometry here, but suffice to say it would provide you with the name of every element contained in a given sample of paper. The problem is that samples differ in composition based upon, in the case of trees, the environment they were grown, nutrient content of soil, seasonal influences, tree age, wood processing methods, paper finishing etc. Additionaly, no two trees have identical cellular chemical composition in the seconds they're cut down to be turned into paper. Nevertheless, typically, element composition of paper would include Cerium, Sodium, Magnesium, Barium, Strontium, Manganese, Aluminium and a whole host of other elements.
Due to this complex elemental structure of paper neither an empirical nor general formula can be allocated to it. It is conventional to state that paper is predominantly composed of cellulose, which in turn contains Carbon, Hydrogen and Oxygen but it is far from being the whole story.