A combinatorics proof
48657
Solving factorial equations
156383
Proving a combinatorial identity without double counting
41205
Help me solve a combinatorial problem
144571
A conjecture including binomial coefficients
134440
An unexpected application of non-trivial combinatorics
23322
Combinatorics Inclusion - Exclusion Principle
154703
Use combinatorics to prove $L\left(n,k\right)=\sum_{j=0}^{n}{ n\brack j}{j\brace k}$
103347
combinatorial proof of summation
86389
Combinatorial argument to prove the recurrence relation for number of derangements
143573
Problem (1.8) A Path to Combinatorics Solution Verification.
15452
Proving determinant product rule combinatorially
152084
Binomial-Theorem proof
76368
Proving the Binomial theorem
142534
Proof of $k {n\choose k} = n {n-1 \choose k-1}$ using direct proof
19571
Combinatorial proof for $\sum_{k = 0}^n \binom {r+k} k = \binom {r + n + 1} n$
97254
What is the proof of permutations of similar objects?
34299
Combinatorial proof of $\sum_{k=0}^n k \cdot k! = (n+1)! -1$