Skip to main content
1 of 4
domotorp
  • 18.7k
  • 3
  • 57
  • 125

Can we color Z^+ with n colors such that a, 2a, ..., na all have different colors for all a?

For example for n=2 coloring odd numbers red, numbers of the form 4k+2 blue and so on works.

This problem was posed in the KoMaL for n+1 prime, if I know well by Geza Kos. I verified it for all n<30, I think with a computerprogram one can easily verify it for much bigger numbers by trying certain periodic colorings.

domotorp
  • 18.7k
  • 3
  • 57
  • 125