Determine the convergence at the points x {\displaystyle x} where the corresponding a n {\displaystyle a_{n}} satisfies lim n → ∞ | a n + 1 a n | = 1 {\displaystyle \lim _{n\rightarrow \infty }{\Big |}{\frac {a_{n+1}}{a_{n}}}{\Big |}=1} .
