Skip to main content
edited tags
Link
GH from MO
  • 105.2k
  • 8
  • 292
  • 398
Source Link

For which values of $k$ is it known that there are infinitely many $n$, such that $2^{n+k}\equiv 1\pmod{n}$?

I know that there are no solutions to $2^n\equiv 1\pmod{n}$ for $n>1$ and I can prove that there are infinitely many $n$ such that $2^{n+1}\equiv1\pmod{n}$.
My question is:

Do we know other fixed values $k\in \mathbb{N}$ such that $2^{n+k}\equiv 1\pmod{n}$ holds infinitely often?