Consider the series

${\displaystyle \underset{n=1}{\overset{}{}}}\frac{(8x{)}^n}{n}$

Find the interval $of$ convergence $of$ this power series $by$ first using the ratio test $to$ find its radius $of$ convergence and then testing the series' behavior $at$ the endpoints $of$ the interval specified $by$ the radius $of$ convergence.

interval $of$ convergence $=$

$(Enter$ your answer $asan$ interval: thus, $if$ the interval $of$ convergence were $,$ you would enter $(-3,5].$ Use Inf for any endpoint $at$ infinity.$)$