For the following power series $$ \sum_{n=1}^{ \infty} \bigg( 1 + \frac{(-1)^n}{n} \bigg)^{ n^2} \frac{(2x+1)^n}{n} $$ I proved that the radius of convergence is $r= \frac{1-e}{2 \ e} $. How may I prove that the interval of convergence is open and not closed?
2026-04-13 01:07:36.1776042456
Field of convergence, prove it's open?
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