We let $p\neq q$ be odd prime numbers and $r$ be integer $>2$. Are there such $p,q$ satisfying $pq=(2^r-1)(p+q)-5$?
This is clear from here that,
$q(p-2^r+1)=(2^r-1)p-5$,
and $p(q-2^r+1)=(2^r-1)q-5$.
Thanks.
We let $p\neq q$ be odd prime numbers and $r$ be integer $>2$. Are there such $p,q$ satisfying $pq=(2^r-1)(p+q)-5$?
This is clear from here that,
$q(p-2^r+1)=(2^r-1)p-5$,
and $p(q-2^r+1)=(2^r-1)q-5$.
Thanks.
Over at tomerg's other, closely-related question The form $xy+5=a(x+y)$ and its solutions with $x,y$ prime I found $p=17179929661$, $q=4880269588100161$, $r=34$ is a solution.
Blockquote EDIT: After writing, the original problem was edited to read $p(q - 2^r - 1)...$ and so this is all beautiful speculation on a different problem. Had I checked his derivation, I might have noticed. But I didn't.
Firstly, I wonder - is there a significance to this question? I've no idea. But I put together some scratch work real quick and found a solution - so there's that.
I note firstly that at most one can be even (considering the equation mod 2 gives this). So I thought, what if p were 2?
Then we have $ 2(q + 2^r - 1) = (2^r - 1)1 - 5$ $ 2^{r+1} + 3 = (2^r - 3)q$ $ \frac{2^{r+1} + 3}{2^r - 3} = q $
And if $ r = 2$, we get that $ q = 11$. Although I don't have it yet, I suspect this is the only solution for q for $p = 2$. So there is at least one answer.
Without having a better intuition for the problem (as I don't really know if there's anything special about this equation, if it means something in particular, etc.), I don't see a better method of attack than this sort of play.