On the Mutual Change of the Coefficients and Values of the Derivative in a Class of Regular Functions

Resumo

Let T be the class of functions \( f(z)=z+\sum \limits_{n=2}^{\infty }{c}_n{z}^n \) regular and typically real in the disk |z| < 1. Sharp estimates for the coefficients c4 and c5 in terms of f′(r) are obtained.