Hankel determinants for starlike functions associated with a cardioid domain
摘要
For starlike functions associated with a cardioid domain, we provide sharp bounds for the Zalcman functional a2a3-a4 and the second and third Hankel determinants. Our result on the third Hankel determinant gives the negative answer to a conjecture given in [L. Shi et al., A study of third Hankel determinant problem for certain subfamilies of analytic functions involving cardioid domain, Mathematics, 7(5):418, 2019].