Counting nondecreasing functions $f: \{1, 2, 3, 4, 5, 6\} \to \{1, 2, 3\}$
25563
Count number of increasing functions, nondecreasing functions $f: \{1, 2, 3, \ldots, n\} \to \{1, 2, 3, \ldots, m\}$, with $m \geq n$.
26569
Counting binary operations on a set with $n$ elements
39090
Finding functions such that $f(g(x)) = f(x)g(x)$
31698
$f(m^2 + f(n)) = f(m)^2 + n$ for all natural numbers
29403
Finding functions $f: \Bbb R_*^+ \to \Bbb R_*^+$ with certain properties
28425
Constructing a sequence of function
24091
How many ways can $r$ nonconsecutive integers be chosen from the first $n$ integers?
41448
Counting set for generating functions
156778
Finding functions satisfying $f(f(x))+f(x)+x=0$
146055
Proving a set of functions is uncountable
103625
Number of increasing functions from $\{1,2,\dots, n\}$ to itself.
116501
How to show equinumerosity of  the powerset of $A$ and the set of functions from $A$ to $\{0,1\}$ without cardinal arithmetic?
97314
Counting nearly-sorted permutations
70327
the numer of partial function between two sets in combinatoric way
25525
Rule for orderless function Times
141225
Number of all bijective functions from A to A.
124140
Quick way to find the number of the group homomorphisms $\phi:{\bf Z}_3\to{\bf Z}_6$?