Counting & ProbabilityEasyRecursion, Catalan Numbers & Generating Functions ShareRecursion, Catalan Numbers & Generating Functions · Easy problemIn the series 11−x3=∑k≥0x3k\dfrac{1}{1-x^3}=\sum_{k\ge0}x^{3k}1−x31=∑k≥0x3k, what is the coefficient of x9x^9x9?Check Show answer Walk through it step by step Practice more like this Review this concept