Combinatorial Identity

For discussing Olympiad Level Combinatorics problems
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Masum
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Combinatorial Identity

Unread post by Masum » Fri Aug 21, 2015 1:50 am

Prove the following:
\[\sum_{k=0}^n\binom{2k}k\binom{2n-2k}{n-k}=4^n\]
One one thing is neutral in the universe, that is $0$.
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