Power Serieshard
0:00.0

The Dirichlet eta function is defined as η(s)=n=1(1)n1ns\eta(s) = \sum_{n=1}^{\infty} \frac{(-1)^{n-1}}{n^s} for s>0s > 0. Consider the power series f(x)=n=1(1)n1xnn2f(x) = \sum_{n=1}^{\infty} \frac{(-1)^{n-1} x^n}{n^2} for x1|x| \leq 1. What is f(1)f(1)?