The authors study the
zero free regions of iterates of multiplier-sequence operators for (i) functions
analytic in the disc |z| < R and (ii) functions analytic in |z| > T. Integral
representations for the iterates of each class of functions are given. As a
consequence the authors give a generalization of the Post-Widder inversion
formula. Other applications include an investigation of the zero free regions
for iterates of fractional integrals as well as connections between results
obtained here and recent final set results for iterates of operators on balanced
sums.