The sum of divisors function $F:\mathbb N\to\mathbb N$ is an arithmetic function, which maps a given number $n\in\mathbb N,$ $n > 0$ to the sum of its divisors. In the sum notation, the $F$ function can be written as $$F(n):=\sum_{d \mid n}d\quad\quad\forall n > 0.$$
The $F$ function can be visualized using SageMath. If you click on the evaluate button, you will see the values of $F(n)$ for $n=1,\ldots,100.$
Definitions: 1
Proofs: 2
Propositions: 3
