3
$\begingroup$

For a prime power $p^a$ define $\gamma(p^a) := (p^a-1)(p^{a-1}-1)\cdots(p^{2}-1)(p-1)$. Moreover, for a natural number $n = \prod {p_{i}}^{\alpha_{i}}$ define $\gamma(n) := \prod \gamma({p_{i}}^{\alpha_{i}}) $ where $p_1,\dots,p_k$ are distinct prime numbers and $\alpha _{i}$ are natural numbers.

The question is that:

If $p$ is a primitive prime divisor of $2^{8n+4} - 1 $, is it true to say $ p \nmid \gamma(\dfrac{2^{8n+4} - 1}{2^{2n+1} + 1}) $?

$\endgroup$

1 Answer 1

7
$\begingroup$

No. We have that $p = 709$ is a primitive prime divisor of $2^{708} - 1$. However, $\frac{2^{708} - 1}{2^{177} + 1}$ is a multiple of the prime $q = 5521693$ and therefore $q-1 | \gamma\left(\frac{2^{708} - 1}{2^{177}+1}\right)$. Since $q \equiv 1 \pmod{709}$, we have that $p | \gamma\left(\frac{2^{708} - 1}{2^{177}+1}\right)$.

$\endgroup$
0

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.