Question Number 85351 by naka3546 last updated on 21/Mar/20
$$\underset{{n}=\:\mathrm{4}} {\overset{\infty} {\sum}}\:\:\frac{{x}^{\mathrm{2}} +\mathrm{2}{x}+\mathrm{3}}{\mathrm{2}^{{x}} \left({x}^{\mathrm{2}} \:+\:\mathrm{4}\right)}\:\:=\:\:? \\ $$