Successive coefficients for spirallike and related functions

We consider the family of all analytic and univalent functions in the unit disk of the form f(z) = z+ a2z2+ a3z3+ ⋯. Our objective in this paper is to estimate the difference of the moduli of successive coefficients, that is | | an+1| - | an| | , for f belonging to the family of γ-spirallike functions of order α. Our particular results include the case of starlike and convex functions of order α and other related class of functions.