On a regular 17-gon
Source: Finnish Mathematics Competition 2002, Final Round, Problem 5
November 14, 2011
geometrycircumcirclemodular arithmeticcombinatorics unsolvedcombinatorics
Problem Statement
There is a regular -gon and its circumcircle on the plane.
The vertices of are coloured in such a way that are of different colour, if the shorter arc connecting and on has vertices, for some including and
What is the least number of colours which suffices?