Coefficient estimates for Ruscheweyh derivatives

Abstract

We consider functions f, analytic in the unit disc and of the normalized form f(z)=z+∑n=2∞anzn. For functions f∈R¯δ(β), the class of functions involving the Ruscheweyh derivatives operator, we give sharp upper bounds for the Fekete-Szegö functional |a3−μa22|.