Question Number 37294 by math khazana by abdo last updated on 11/Jun/18
$${let}\:{D}\:={D}\left(\mathrm{0},\mathrm{1}\right)\:{and}\:{f}\left({z}\right)\:=\sum_{{n}=\mathrm{0}} ^{\infty} \:{a}_{{n}} {z}^{{n}} \:{is}\:{a}\:{holomorphe} \\ $$$${function}\:/\:\:\mid{f}\left({x}\right)\mid<\:\:\frac{\mathrm{1}}{\mathrm{1}−\mid{z}\mid}\:\:{prove}\:{that} \\ $$$$\mid{a}_{{n}} \mid\leqslant\:\left({n}+\mathrm{1}\right)\left(\mathrm{1}+\frac{\mathrm{1}}{{n}}\right)^{{n}} \leqslant\left({n}+\mathrm{1}\right){e}. \\ $$