Number of ways pairs can sit so that no husband and wife sit together
140806
How do I tackle this combinatorics problem about married couples around a table?
146098
Number of nonempty subsets of a set with $n$ elements
96803
Hall's marriage theorem in bipartite graph
74772
How many arrangements of a bookshelf exist where certain books must be to the left/right of other books?
13190
Rearranging people so that no one is in the same spot
150679
Number of n-words such that a and b are not neighbors.
72750
Uncountable number of mutually disjoint countable sets in $\mathbb R$
57822
Number of ways to choose two disjoint subsets of a set
84910
Generate some number of lists of pairs given a list of people
134888
Ethical ways to dissuade?
133436
Inclusion-Exclusion: INTELLIGENT permutations
122539
Arrange $m$ people in $m+r$ seats around a round table.
81892
Find four groups of order 20 not isomorphic to each other.
71098
number of table with $1$ and $-1$
134440
An unexpected application of non-trivial combinatorics
61653
How to play with friends who don't want to read the rules?
124290
Shuffle list, ensuring that no item remains in same position