$[a_{i,j}]_{n\times n}=\left[ \begin{array}{ccc} 1&4&32&...\\ 2&16&...&...\\ 8&...&...&...\\ ...&...&...&...\\ \end{array}\right]$, find $a_{3,7}$
116824
Find the sum of two elements in a matrix
85195
Recurrence relation: $a_n = 3a_{n-1} + 2n, a_0 = 1$
138271
Find the least number which when divided by 2, 3, 4, 5, 6 leaves a remainder of 1 but it is divided by 7 completely.
49741
Finding a closed form for a recurrence relation $a_n=3a_{n-1}+4a_{n-2}$
61871
Formula for the $n$th term of $1, 2, 2, 3, 3, 3, 4, 4 ,4, 4, 5, ...$
133017
Prove that $n^n>1\times3\times5\times7\times \dots\times(2n-1)$
113789
Given that$(3x-1)^7=a_7x^7+a_6x^6+a_5x^5+...+a_1x+a_0$, find $a_7+a_6+a_5+a_4+...+a_1+a_0$
111324
Finding number of relations on a set with 3 elements
97656
Finding $a_n$ if $a_0=a_1=1,a_{n+1}=n(a_n+a_{n-1})\ \ (n\ge 1).$
41641
$(n-7)(n+7)=$ some perfect square
12100
$n \mid (a^{n}-b^{n}) \ \Longrightarrow$ $n \mid \frac{a^{n}-b^{n}}{a-b}$
33216
Prove that the order of an element in $S_n$ equals the least common multiple of the lengths of the cycles in its cycle decomposition.
142477
Closed-form expression for the number of $k$-permutations of length $n$. Duplicates allowed!
111555
Find $a,b \in \mathbb{N}$ with $\mathrm{lcm}(a,b)=12\gcd(a,b)\,$ and $\,a\bmod b = 5$
150166
What is $P([a_1,b_1]\times [a_2,b_2]\times...\times[a_k,b_k])$
140143
Find $n$ satisfying the equation $[\log_21]+[\log_22]+[\log_23]+\dots[\log_2n]=1538 $
114262
Find the cardinality of the following set $S_n=\{(x,y)|x^2+y^2=n, \text{where }x,y,n \in \mathbb Z\text{ and }n\geq0 \}$