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We determine sharp bounds on some Hankel determinants involving initial coefficients, inverse coefficients, and logarithmic inverse coefficients for two subclasses of Sakaguchi functions which are associated with the right half of the…

Complex Variables · Mathematics 2023-08-23 Sushil Kumar , Rakesh Kumar Pandey , Pratima Rai

This paper deals with sharp bounds for the third-order Hankel, Toeplitz and Hermitian-Toeplitz determinant of functions belonging to the class $\mathcal{S}^*_{B}$ of starlike functions associated with a balloon-shaped domain, given by \[…

Complex Variables · Mathematics 2026-03-12 S. Sivaprasad Kumar , Arya Tripathi

Let $\mathcal{A}$ denote the class of normalized analytic functions $f$ in the open unit disk defined as $ \mathbb{D}:=\{z\in\mathbb{C}:|z|<1\} $ with $f(0)=0$ and $f'(0)=1$. A function $f\in\mathcal{A}$ is said to be starlike if…

Complex Variables · Mathematics 2026-04-28 Vasudevarao Allu , Shobhit Kumar

This note presents some results about Hankel determinants of backwards shifted Catalan-like numbers and related sequences.

Combinatorics · Mathematics 2024-04-16 Johann Cigler

In the present investigation the authors obtain upper bounds for the second Hankel determinant of the classes bi-starlike and bi-convex functions of order beta.

Complex Variables · Mathematics 2015-10-08 Erhan Deniz , Murat Çağlar , Halit Orhan

Using some properties of the Grunsky coefficients we improve earlier results for upper bounds of the Hankel determinants of the second and third order for the class $\mathcal{S}$ of univalent functions.

Complex Variables · Mathematics 2024-11-20 Milutin Obradović , Nikola Tuneski

Let $f$ be analytic in the unit disk $\mathbb D$ and normalized so that $f(z)=z+a_2z^2+a_3z^3+\cdots$. In this paper, we give upper bounds of the Hankel determinant of second order for the classes of starlike functions of order $\alpha$,…

Complex Variables · Mathematics 2019-12-30 Milutin Obradovic , Nikola Tuneski

In this current study, we consider the classes $\mathcal{S}^{*}_{e}$ and $\mathcal{C}_e$ to obtain sharp bounds for the third Hankel determinant for functions within these classes. Additionally, we provide estimates for the sixth and…

Complex Variables · Mathematics 2023-09-07 S. Sivaprasad Kumar , Neha Verma

In this note, we present the determinant, the inverse and a lower bound for the smallest eigenvalue for some Hankel matrices

Classical Analysis and ODEs · Mathematics 2009-06-23 Ruiming Zhang

In this paper, we investigate the sharp bounds of the second Hankel determinant of Logarithmic coefficients for the starlike and convex functions with respect to symmetric points in the open unit disk.

Complex Variables · Mathematics 2021-12-07 Vasudeavarao Allu , Vibhuti Arora , Amal Shaji

The Hankel determinant $H_{2,1}(F_{f^{-1}}/2)$ of logarithmic coefficients is defined as: \begin{align*} H_{2,1}(F_{f^{-1}}/2):= \begin{vmatrix} \Gamma_1 & \Gamma_2 \Gamma_2 & \Gamma_3 \end{vmatrix}=\Gamma_1\Gamma_3-\Gamma^2_2, \end{align*}…

Complex Variables · Mathematics 2023-07-28 Sanju Mandal , Molla Basir Ahamed

We consider a family of all analytic and univalent functions (i.e., one-to-one) in the unit disk $\mathbb{D}:=\{z\in \mathbb{C}:|z|<1\}$ of the form $f(z)=z+a_2z^2+a_3z^3+\cdots$. In this paper, we obtain the sharp bounds of the second…

Complex Variables · Mathematics 2021-12-09 Vasudevarao Allu , Vibhuti Arora

By prepending zeros to a given sequence Hankel determinants of backward shifts of this sequence become meaningful. We obtain some results for the sequences of Catalan numbers and of some numbers and polynomials which are related to Catalan…

Combinatorics · Mathematics 2023-06-14 Johann Cigler

We prove a conjecture concerning the third Hankel determinant, proposed in ``Anal. Math. Phys., https://doi.org/10.1007/s13324-021-00483-7", which states that $|H_3(1)|\leq 1/9$ is sharp for the class $\mathcal{S}_{\wp}^{*}=\{zf'(z)/f(z)…

Complex Variables · Mathematics 2022-08-08 Neha Verma , S. Sivaprasad Kumar

In this paper we investigate Toeplitz and symmetric Toeplitz determinants of inverse functions for some classes of univalent functions and improve some previous results.

Complex Variables · Mathematics 2025-12-25 Milutin Obradović , Nikola Tuneski

In the present study, we consider two subclasses starlike and convex functions, denoted by $\mathcal{S}_{\mathcal{B}}^{*}$ and $\mathcal{C}_{\mathcal{B}}$ respectively, associated with a bean-shaped domain. Further, we estimate certain…

Complex Variables · Mathematics 2024-05-15 S. Sivaprasad Kumar , Neha Verma

Let $f$ be analutic in the unit disk $\mathbb D$ and normalized so that $f(z)=z+a_2z^2+a_3z^3+\cdots$. In this paper we give sharp bound of Hankel determinant of the second order for the class of analytic unctions satisfying \[ \left|\arg…

Complex Variables · Mathematics 2019-03-20 Milutin Obradovic , Nikola Tuneski

A general method of finding functional determinants is presented that depends on the asymptotic behaviour of the resolvent. Its application to the case of a bounded trihedral corner for which the eigenvalues are known only implicitly is…

High Energy Physics - Theory · Physics 2022-04-13 J. S. Dowker

Following the trend of coefficient bound problems in Geometric Function Theory, in the present paper, we obtain the sharp bound of $|H_3(1)|$ for the class $\mathcal{S}^*$, of starlike functions and $\mathcal{SL}_q^*$, of $q$- starlike…

Complex Variables · Mathematics 2022-01-19 Shagun Banga , S. Sivaprasad Kumar

The middle binomial coefficients can be interpreted as numbers of Motzkin paths which have no horizontal steps at positive heights. Assigning suitable weights gives some nice polynomial extensions. We determine the Hankel determinants and…

Combinatorics · Mathematics 2022-01-03 Johann Cigler