Combinatorial Proof, Binomial Coefficients
32780
Combinatorial Proof Question: Vandermonde convolution identity
39724
Combinatorial Identities
116356
Combinatorial proof of $2 \cdot 3^0 + 2 \cdot 3^1 + 2 \cdot 3^2 + \cdots 2 \cdot 3^{n-1} = 3^n-1$
67927
Combinatorial argument for the identity $k\binom{n}{k} = n\binom{n-1}{k-1}$
14986
Proving a combinatorics equality: $\binom{r}{r} + \binom{r+1}{r} + \cdots + \binom{n}{r} = \binom{n+1}{r+1}$
106008
Combinatorial Identity $(n-r) \binom{n+r-1}{r} \binom{n}{r} = n \binom{n+r-1}{2r} \binom{2r}{r}$
59831
How to relate combinatorial proof to bipartite graphs?
89576
Proof of a binomial identity $\sum_{k=0}^n {n \choose k}^{\!2} = {2n \choose n}.$
91648
Binomial coefficient proof
28936
Proving equation with binomial coefficient
10917
Give a combinatorial proof: $ n(n+1)2^{n-2} = \sum_{k=1}^{n}k^2\binom{n}{k} $
156383
Proving a combinatorial identity without double counting
140632
A problem on Binomial Theorem
67844
Prove equation with binomial coefficient
92704
Prove that $\sum_{k=1}^{n}k\binom{n}{k}=n\cdot2^{n-1}$
82872
Combinatorial proof involving partitions and generating functions
152911
Stirling numbers combinatorial proof