Question Number 131159 by mohammad17 last updated on 02/Feb/21
Commented by mohammad17 last updated on 02/Feb/21
$${who}\:{can}\:{solve}\:{this}\:? \\ $$
Commented by mohammad17 last updated on 02/Feb/21
$${chouse}\:{the}\:{right}\:{answer} \\ $$
Commented by EDWIN88 last updated on 02/Feb/21
$${a}_{{n}} =\:\frac{\left(\mathrm{2}{n}+\mathrm{3}\right)!}{\left({n}+\mathrm{1}\right)!}\:=\:\frac{\left(\mathrm{2}{n}+\mathrm{3}\right)\left(\mathrm{2}{n}+\mathrm{2}\right)!}{\left({n}+\mathrm{1}\right)!} \\ $$$$\:\:\:\:\:=\: \\ $$