Fekete–Szegö problem for starlike and convex functions of complex order

For nonzero complex bb let Fn(b)Fn(b) denote the class of normalized univalent functions ff satisfying Re [1+(z(Dnf)′(z)/Dnf(z)−1)/b]>0 in the unit disk UU, where DnfDnf denotes the Ruscheweyh derivative of ff. Sharp bounds for the Fekete–Szegö functional |a3−μa22| are obtained.