Fourth Hankel determinant and logarithmic coefficients for starlike functions associated with the cosine function

• Datum: 2026
• Hauptverfasser: Ali, Rashid, Raza, Mohsan, Bulboacă, Teodor
• Format: Artikel
• Sprache: Englisch
• Veröffentlicht: Institute of Mathematics, NAS of Ukraine 2026
• Online Zugang: https://umj.imath.kiev.ua/index.php/umj/article/view/9403
• Назва журналу: Ukrains’kyi Matematychnyi Zhurnal

UDC 517.53, 517.54 Let $\mathcal{\mathcal{S}}_{\cos}^{\ast}$ be a class of normalized analytic functions $f$ in an open unit disk $\mathbb{D}$ satisfying the subordination $\dfrac{zf^{\prime}(z)}{f(z)}\prec\cos z.$ The aim of the present article is to find upper bounds for the module of some coeffic...