General theory of modular invariants
Leonard Eugene Dickson · Transactions of the American Mathematical Society · 1909
The replacement of a group by any set of transformations is only an apparent generalization, t A polynomial in the coeficiente o¡ of the forms, each a entering to a power ^ pn -1, as may be assumed in view of at>" = a.* By introducing notations to indicate which of the numbers e, are equal, we may readily give an explioit formula for the total number of invariants, as well as the number of relative invariants of each weight.For example, the number of absolute invariants is p*f.