Hankel determinant for a certain subclass of analytic functions

Abstract

In this paper, we investigate the bound of the second Hankel determinant H2(2) = a2a4- a23 for the coefficients of a function f belonging to the class W α,β (ϕ) of all normalized analytic functions in the open unit disk U, satisfying the following differential subordination: (1 - α + 2 β) f(z)/z + (α-2 β) f’(z) + βzf’’(z) < ϕ (z).