Marjono, D.K. Thomas
It is shown that if f is analytic in z ∈ D = (z: |z| < 1) with f(z) = z + Σ∞n=2 anzn, and is convex in one direction, then the second Hankel determinant H2(2) = |a2a4 - a23| ≤ 1. The inequality is sharp. © 2016 Marjono and D. K. Thomas.
Faculty of Mathematics and Natural Sciences, University of Brawijaya, Malang, Jawa Timur, 65145, Indonesia; Department of Mathematics, Swansea University, Singleton Park, Swansea, SA2 8PP, United Kingdom
