How many different chains in a Poset?
33894
How many chains are there in a finite power set?
144821
Number of ordered pairs of subsets
98518
Cardinality of equivalence relations on N
41008
how many permutations of {1,2,...,9}
84132
Number of preimages of a group element under a homomorphism.
149609
Conditions on cycle types for permutations to generate $S_n$
74114
How to find the number of anti-symmetric relations?
153306
Number of sigma algebras for set with 4 elements
16687
Number of Equivalence relations of $\{1,2,3\}$
933
How many groups exist with order $n$ (two isomorphic groups are treated as the same group)
26343
Number of certain (0,1)-matrices, Stanley's Enumerative Combinatorics
113668
Uncountable chain of subsets of $\mathbb N$
50798
Initial Segments and Initial Sections of Posets
24212
proving how many permutations exist.
104112
Number of finite simple groups of given order is at most $2$ - is a classification-free proof possible?
94033
What is the expected value of the number of anchors of $S$?
35362
Number of equivalence relations on a set