On the coefficient problem for close-to-convex functions.

This paper is concerned with the problem of estimating |a₄ -a₂a₃|, where ak are the coefficients of a given close-to-convex function. The bounds of this expression for various classes of analytic functions have been applied to estimate the third Hankel determinant H₃(1) . The results for two subclasses of the class C of all close-to-convex functions are sharp. This bound is equal to 2. It is conjectured that this number is also the exact bound of |a₄ -a₂a₃| for the whole class C. [ABSTRACT FROM AUTHOR]