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Results tagged with co.combinatorics
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user 430953
Enumerative combinatorics, graph theory, order theory, posets, matroids, designs and other discrete structures. It also includes algebraic, analytic and probabilistic combinatorics.
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Prove the identity $2(n-1)n^{n-2} = \sum^{n-1}_{i=1}\binom nii^{i-1}(n-i)^{n-i-1}$ [closed]
The given identity:
$$2(n-1)n^{n-2} = \sum^{n-1}_{i=1}\binom nii^{i-1}(n-i)^{n-i-1}$$
It seems to be a binomial coefficient problem, but I have tried many ways. There are no more ideas how to prove it …
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