Has it been proved or disproved that for any fixed $a\geq 1$ there are infinitelly many primes $p_n\equiv a\pmod{n}$?
I believe i have proved that for every $a\geq1$ there are infinitelly many natural numbers $m$ with $m\equiv a\pmod{\pi(m)}$ where $\pi(m)$ is the prime counting function and i was wondering if this can be also true for a smallest subset of $\mathbb{N}$ (the primes).

OEIS does not tell much.http://oeis.org/A004648
Any reference would be appreciated.
Thank you for viewing.

  • $\begingroup$ How did you prove that $m\equiv a\pmod{\pi(m)}$ has infinitely many solutions $m$ for any fixed $a$? $\endgroup$ – Michael Zieve Oct 31 '13 at 23:54
  • $\begingroup$ @Michael Zieve using the fact that $\pi(m)=\omicron(m)$ and that $\pi(m+1) -\pi(m)=0$ or $1$. If you divide $m-a$ with $\pi(m)$ the residue must be sometimes zero because if not, $\frac{m-a}{\pi(m)}$ will be always too small.In fact i believe that this same argument could be applied not only to a fixed $a$ but to any slowly increasing sequence $a(m)$ of natural numbers as well.But this is just hypothetical. $\endgroup$ – Konstantinos Gaitanas Nov 1 '13 at 0:15

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.