Divisor Sum of 343

Example of Sigma of Power of Prime

 * $\sigma \left({343}\right) = 400$

where $\sigma$ denotes the $\sigma$ function.

Proof
From Sigma of Power of Prime:
 * $\sigma \left({p^k}\right) = \dfrac {p^{k + 1} - 1} {p_i - 1}$

We have that:
 * $343 = 7^3$

Hence: