number of subsets of even and odd
21152
Exactly half of the elements of $\mathcal{P}(A)$ are odd-sized
123267
Proving that even numbers equal the sum of two odd numbers.
5118
Show that $n ≤ 100$ if $ \{A_1,A_2,... ,A_n\}$ is a set of distinct $3$-element subsets of $\{1, 2,... , 36\}$ such that...
64519
Subsets of a list
99634
$\binom{n}{1},\binom{n}{2},\ldots ,\binom{n}{n-1}$ are all even numbers.
92554
How many lattice paths are there from $(0,0)$ to $(2n,2n)$ that avoids odd points
83837
Odd/Even Permutations
134440
An unexpected application of non-trivial combinatorics
2731
Groups of even order have an element whose order is 2.
85272
$3x + 1$ is even iff $5x-2$ is odd
65764
Partitioning $\{1,2,\ldots,k\}$ into $p$ subsets with equal sums, where $p$ is prime
158507
Max family of odd subset of a nested set.
72767
Center of the dihedral group with odd and even number of vertices
40030
FA that accepts odd number of $b$ and even number of $a$
38466
Proving that the number of vertices of odd degree in any graph G is even
155690
Recurrences for even and odd indexed of Fibonacci Numbers
79984
Partition of ${1, 2, ... , n}$ into subsets with equal sums.