The probability that exactly / at-least $k$ numbers are in the correct position
11182
Derivation of the Partial Derangement (Rencontres numbers) formula
147079
$\gcd\left(\binom{n}{k},n\right)>1$ for nontrivial values?
63129
Infinite number of $k$ satisfying $p_{k+1} - p_{k} > 2$?
109826
Probability of list having a pair of unchanged consecutive elements once ordered
57754
Probability of exactly two heads in four coin flips?
76445
Counting the exact number of coin tosses
47240
An alternate solution to the hat-matching problem, probability of exactly $k$ matches
9009
$n$ choose $k$ where $n$ is less than $k$
135696
Probability of an even number of sixes
122530
Number of zeros at the end of $k!$
15239
Probability that a sequence repeats itself
104191
probability that 5 square lie along a diagonal line (modified)
29713
$k$ times's draw from $n$ numbers with replacement, each number at least appear once
117434
Counting integer partitions of n into exactly k distinct parts size at most M
39005
Probability that a number has $m$ indistinct factors
119129
Determining whether there is a short exact sequence
6874
smallest value of $k$ for which $a_k$ is $0$