Primitive Abundant Number/Examples/650
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Example of Primitive Abundant Number
$650$ is a primitive abundant number:
- $1 + 2 + 5 + 10 + 13 + 25 + 26 + 50 + 65 + 130 + 325 = 652 > 650$
Proof
From $\sigma_1$ of $650$, we have:
- $\map {\sigma_1} {650} - 650 = 652$
where $\sigma_1$ denotes the divisor sum function: the sum of all divisors of $650$.
Thus, by definition, $650$ is an abundant number.
The aliquot parts of $650$ are enumerated at $\sigma_0$ of $650$:
- $1, 2, 5, 10, 13, 25, 26, 50, 65, 130, 325$
By inspecting the divisor sum of each of these, they are seen to be deficient.
Hence the result, by definition of primitive abundant number.
$\blacksquare$