et F (z) = z? £ cnz", n— 0 where the coefficients are determined by a recurrence reiation Cn-- S (C 0> C 1 > • • • » c n~l). (1) in which g is an algebraic polynomial of degree m in the va- riables cr , that is, it is the sum of homogeneous polynomials go, gm- Each gr is of the form gr ’ f c p1 c />2 • • • c pr P l> P z’ ---,P r