##
Circular Tracks

Several cars, conveniently numbered 0 to N,
are driving in different lanes on a circular track.
For **i** between 0 and N-1,
if the driver in car **i**
looks straight ahead, he always sees car **i+1**.
If the driver in car **N** looks directly
at the center of the track, he always sees car **0**.
What are the possible values
of (s,k,N) for which this holds true if the speed of car **i** is:
- s+ki?
- s*(k^i)?

For example, this will work in case 2 if k=2 and N=6. Each car will
be progressively 60 degrees farther around the track.
Source: Original.

Solution

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