Difference between revisions of "Sum of divisors"

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The sum of positive divisors function, $\sigma_x$, is defined by
+
The sum of positive divisors function, $\sigma$, is defined by
$$\sigma_x(n) = \displaystyle\sum_{d|n} d^x,$$
+
$$\sigma(n) = \displaystyle\sum_{d|n} d,$$
 
where $d|n$ denotes that $d$ is a [[divisor]] of $n$.
 
where $d|n$ denotes that $d$ is a [[divisor]] of $n$.

Revision as of 21:46, 16 August 2015

The sum of positive divisors function, $\sigma$, is defined by $$\sigma(n) = \displaystyle\sum_{d|n} d,$$ where $d|n$ denotes that $d$ is a divisor of $n$.