Primitive Abundant Number/Examples/272
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Example of Primitive Abundant Number
$272$ is a primitive abundant number:
- $1 + 2 + 4 + 8 + 16 + 17 + 34 + 68 + 136 = 286 > 272$
Proof
From $\sigma_1$ of $272$, we have:
- $\map {\sigma_1} {272} - 272 = 286$
where $\sigma_1$ denotes the divisor sum function: the sum of all divisors of $272$.
Thus, by definition, $272$ is an abundant number.
The aliquot parts of $272$ are enumerated at $\sigma_0$ of $272$:
- $1, 2, 4, 8, 16, 17, 34, 68, 136$
By inspecting the divisor sum of each of these, they are seen to be deficient.
Hence the result, by definition of primitive abundant number.
$\blacksquare$