A really cool combinatorics problem / puzzle
15349
Combinatorics riddle: keys and a safe
68882
Path to Combinatorics Problem [$1.11$]
126297
A high school Olympiad problem
89611
Combinations of selecting $n$ objects with $k$ different types
10272
A three-way duel (probability puzzle)
13860
IMO/1981 - Combinatorics
87968
A strange puzzle having two possible solutions
107110
Solving Rubik's cube and other permutation puzzles
20722
Fixed points in random permutation
113953
Circular permutations with indistinguishable objects
86067
A Variation of the even-town odd-town problem
96585
Sums and permutation
24212
proving how many permutations exist.
70761
Number of ways to connect sets of $k$ dots in a perfect $n$-gon
144571
A conjecture including binomial coefficients
42270
Combinatorics - Painting the Unit Squares of a 3x3 Square
61483
Prove the following identity combinatorially