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MathNet 2009-part-04 — 175 problems (EN–VI) Question 112

Math Olympiad Vault · MathNet 2009-part-04 — 175 problems (EN–VI)

Question 112

Prove for any positive integer $n$:
$$
\sum_{k=0}^{n-1} \frac{\left(\binom{n-1}{k}\right)^2}{k+1} = \frac{\binom{2n}{n}}{2n}
$$