$\displaystyle a_n=\left(\sqrt{2}\right)^n$\displaystyle a_n=\left(\sqrt{2}\right)^n

$\displaystyle a_n= \frac{2^n}{\sqrt{2}}$\displaystyle a_n= \frac{2^n}{\sqrt{2}}

$\displaystyle a_n=\left( \frac{\sqrt{2}}{2} \right)^n$\displaystyle a_n=\left( \frac{\sqrt{2}}{2} \right)^n

$\displaystyle a_n= \frac{\left(\sqrt{2}\right)^n}{2}$\displaystyle a_n= \frac{\left(\sqrt{2}\right)^n}{2}