Formula for: If $X$ is a set of $t$ elements,the number of ordered, $k$-element selections from $X$, limitless repetition allowed is
53639
Formula for number of 6 letter words from English alphabet if there is repetion and ordering
69943
why is ${n+1\choose k} = {n\choose k} + {n\choose k-1}$?
136069
Is there a simple formula for the cardinality of $\{A\subseteq\kappa\mid |A|\leq\lambda\}$ when $\lambda\leq\kappa$?
8173
Number of ways to choose $n$ balls from $3n$ balls, distinguishable/indistinguishable.
40937
Is the set of partial order relations over $ \mathbb{N}$ countable?
57954
How many transitive relations on a set of $n$ elements?
20478
Mathematical expression for $n$ largest values in a set
117862
Number of partitions of an $n$-element set into $k$ classes
19414
Uncountable subset with uncountable complement, without the Axiom of Choice
62175
A general formula for $n$ distinguishable arrangements of length $\ell$ of a sequence of a given size?
76405
Let n be an even integer. How many different ways can I choose subsets of the set {1,2...,n}
26343
Number of certain (0,1)-matrices, Stanley's Enumerative Combinatorics
142534
Proof of $k {n\choose k} = n {n-1 \choose k-1}$ using direct proof
84394
Choice function for a collection of nonempty subsets of $\{0,1\}^\omega$
152838
Relation between Ramsey Numbers: $R(s, t) > (t-1)(s-1)$
9850
How many ways are there to choose 3 subsets $A,B,C$ of a set $\{1,2,3...n\}$ such that $ A \cap B \cap C = \emptyset $
121097
Every not empty finite subset of a totally ordered set has a maximum and minimum