Combinatorics - find $n!$ using inclusion-exclusion
20618
Expressing a factorial as difference of powers: $\sum_{r=0}^{n}\binom{n}{r}(-1)^r(l-r)^n=n!$?
140416
Catalan number - combinatoric
151935
Proving the predicate $\forall n \in \mathbb{N} , n \geq 2$ using the Pigeonhole principle
30003
Proving that Order for N is Anti-symmetric
20221
Combinatorics - Removing Double Counted Cases
138304
getting tight bounds on n!
83841
Mutual Exclusion Problem
134570
Using Inclusion/Exclusion to solve $x_1+x_2+x_3=15$ with $x_1,x_2\leq 5$ and $x_3\leq 7$ for non negative integers $x_1,x_2,x_3$
143573
Problem (1.8) A Path to Combinatorics Solution Verification.
8458
Combinatorics problem based on Ferrers graph
70282
Help finding a combinatorial proof of $k {n \choose k } = n {n - 1 \choose k -1}$
5215
Can the principle of inclusion/exclusion be used to count elements in the intersection of a sequence of sets?
142477
Closed-form expression for the number of $k$-permutations of length $n$. Duplicates allowed!
96086
Double Factorial: Number of possibilities to partition a set of $2n$ items into $n$ pairs
70327
the numer of partial function between two sets in combinatoric way
45204
Combinatorial proofs: having a difficult time understanding how to write them out
91451
find all positive integer $m,n$