Provide a combinatorial proof that:
(2n choose n) = Sum from k=0 of n of [n choose k]^2
I have a couple starting points but I'm not sure if they qualify as a combinatorial proof. Any ideas on how to start this?
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Provide a combinatorial proof that:
(2n choose n) = Sum from k=0 of n of [n choose k]^2
I have a couple starting points but I'm not sure if they qualify as a combinatorial proof. Any ideas on how to start this?
See the end of this subsection of the Wikipedia article about the binomial coefficients.