Definition:Aliquot Sum

Definition
Let $n \in \Z$ be a positive integer.

The aliquot sum $\map s n$ of $n$ is defined as the sum of its aliquot parts:


 * $\map s n = \map {\sigma_1} n - n$

where $\map {\sigma_1} n$ denotes the divisor sum of $n$.

Also see

 * Definition:Untouchable Number


 * Definition:Aliquot Part