Power Serieshard
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Let f(x)=n=0xnf(x) = \sum_{n=0}^{\infty} x^n and g(x)=n=1(1)n+1nxng(x) = \sum_{n=1}^{\infty} \frac{(-1)^{n+1}}{n} x^n. Using the Cauchy product formula, find the coefficient of x3x^3 in f(x)g(x)f(x) \cdot g(x).