(Note: This post was copied verbatim from this MSE question.)
Let \sigma(x) be the sum of the divisors of x. Denote the deficiency of x by D(x) := 2x - \sigma(x), and the sum of the aliquot divisors of x by s(x) := \sigma(x) - x.
Here is my question:
If q^k n^2 is an odd perfect number with Euler prime q, does this equation imply that k=1?
D(q^k)D(n^2)=2s(q^k)s(n^2)
I only know that k=1 is true if and only if (one of) the following conditions hold:
(1) \sigma(n^2)/q \mid n^2
(2) D(n^2) \mid n^2
(3) \gcd(n^2, \sigma(n^2)) = D(n^2)
Source of Equation
From the fundamental equation
\frac{\sigma(n^2)}{q^k} = \frac{2n^2}{\sigma(q^k)} = \gcd(n^2, \sigma(n^2))
we obtain
\frac{2n^2 - \sigma(n^2)}{\sigma(q^k) - q^k} = \frac{D(n^2)}{s(q^k)} = \gcd(n^2, \sigma(n^2))
and
\frac{\sigma(n^2) - n^2}{\frac{2q^k - \sigma(q^k)}{2}} = \frac{2s(n^2)}{D(q^k)} = \gcd(n^2, \sigma(n^2)),
using the identity
\frac{A}{B}=\frac{C}{D}=\frac{C-A}{D-B}.
Reference