New posts in Divisors Multiples

Is there a similar formula like Ramanunjan's Eisenstein series identity for $\sum_{k=1}^{n-1}k^2 \sigma(k)\sigma(n-k)$?

Estimating $\sum_{n\leq x: n \in A} d(n)^a$ from below for large sets $A\subset \{1,2,\ldots,x\}.$

Number of matrices with bounded products of rows and columns

Does the Prime Number Theorem have anything to do with Erdos-Kac law or vice versa?

Why do primes dislike dividing the sum of all the preceding primes?

g.c.d. and Euler's totient function

Sum of the sum-of-divisors function

A truncated divisor function sum

On Robin's criterion for RH