RT - Journal Article T1 - Bi-concave Functions Defined by Al-Oboudi Differential Operator JF - IJMSI YR - 2022 JO - IJMSI VO - 17 IS - 1 UR - http://ijmsi.ir/article-1-1408-en.html SP - 207 EP - 217 K1 - Bi-concave functions K1 - Al-Oboudi differential operator K1 - Coefficient estimates. AB - The purpose of the present paper is to introduce a class $D_{Sigma ;delta }^{n}C_{0}(alpha )$ of bi-concave functions defined by Al-Oboudi differential operator. We find estimates on the Taylor-Maclaurin coefficients $leftvert a_{2}rightvert $ and $leftvert a_{3}rightvert$ for functions in this class. Several consequences of these results are also pointed out in the form of corollaries. LA eng UL http://ijmsi.ir/article-1-1408-en.html M3 10.52547/ijmsi.17.1.207 ER -