Let A be a subset of {1, 2, 3 ... 2n-1, 2n} containing n + 1 elements. (Full Question below)
75852
Using Pigeonhole Principle to prove two numbers in a subset of $[2n]$ divide each other
65978
How many subsets does the set $\{1, 2, \dots , n\}$ have that contain no two consecutive integers if $1$ and $n$ also count as consecutive?
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...
55023
if $A$ subset of $B$ then $P(B)-P(A)=P(B\setminus A)\ge 0$
77128
Necessary and Sufficient conditions for $(i \, j)$ and $(1 \, 2 \, \dotsc \, n)$ generate $S_n$.
60804
About the property of $m$: if $n < m$ is co-prime to $m$, then $n$ is prime
124325
Element of, subset of and empty sets
51617
What is the proof that the total number of subsets of a set is $2^n$?
97805
$n+1$ is a divisor of $\binom{2n} {n}$
17212
The preimage of a subset
108807
Subset of a cartesian product
72256
Prove there exists two sub-sets of indices $I,J\subseteq [2n]$ such that $\sum_{i\in I}a_i=\sum_{j\in J}b_j$
86902
Consider the smallest number in each of the $n\choose r$ subsets (of size $r$) of $S=\{1,2,\ldots,n\}$...
35553
If $n$ is composite, so is $2^n-1$
20973
How can I find all the subsets of a set, with exactly n elements?
9411
Number of permutations of $n$ elements where no number $i$ is in position $i$
35660
Elements of order 2 in $D_{2n}$