Question Number 166516 by naka3546 last updated on 21/Feb/22
$$\mathrm{Determine}\:\:\mathrm{the}\:\:\mathrm{formula}\:\:\mathrm{of}\:\:\mathrm{this}\:\:\mathrm{expression} \\ $$$$\:\:\:\underset{{k}=\mathrm{0}} {\overset{{n}} {\sum}}\:\frac{\mathrm{1}}{\left({n}−{k}\right)!\left({n}+{k}\right)!}\: \\ $$