Second hankel determinant for a class of analytic functions defined by a linear operator

Abstract

By making use of the linear operator Θ λ,nm, m ε N = {1,2,3, . . .} and λ, n ε N 0 = NU{0} given by the authors, a class of analytic functions S λ,nm(α, σ)(|α| < 1) is introduced. The object of the present paper is to obtain sharp upper bound for functional |a 2a 4 - a 23|.