Question Number 153105 by alisiao last updated on 04/Sep/21 | ||
$${find}\:\:\boldsymbol{{ln}}\:\boldsymbol{\Gamma}\left(\boldsymbol{{x}}\right)\:? \\ $$ | ||
Answered by puissant last updated on 04/Sep/21 | ||
$${ln}\left(\Gamma\left({x}\right)\right)=β\gamma{x}β{lnx}+\underset{{k}=\mathrm{1}} {\overset{\infty} {\sum}}\left\{\frac{{x}}{{k}}β{ln}\left(\mathrm{1}+\frac{{x}}{{k}}\right)\right\} \\ $$$$=\left({x}β\frac{\mathrm{1}}{\mathrm{2}}\right){lnx}β{x}+\frac{\mathrm{1}}{\mathrm{2}}{ln}\left(\mathrm{2}\pi\right)+\frac{\mathrm{1}}{\mathrm{2}}\underset{{n}=\mathrm{2}} {\overset{\infty} {\sum}}\frac{\left({n}β\mathrm{1}\right)}{{n}\left({n}+\mathrm{1}\right)}\zeta\left({n},{x}+\mathrm{1}\right) \\ $$$$=\left({x}β\frac{\mathrm{1}}{\mathrm{2}}\right){lnx}β{x}+\frac{\mathrm{1}}{\mathrm{2}}{ln}\left(\mathrm{2}\pi\right)+\mathrm{2}\int_{\mathrm{0}} ^{\infty} \frac{{arctan}\left(\frac{{x}}{{a}}\right)}{{e}^{\mathrm{2}\pi{x}} β\mathrm{1}}{dx}. \\ $$ | ||