Anyone who works with gears knows a closed gears train must always have an even number of gears, or it will be locked. Unless you have gears that do not invert rotation on each pair. Then you can have any number you want, even or odd.
Modeled with Solidworks 2020 Student.
Animated with Simlab Composer 8.
Video at https://youtu.be/g0ZoLNdPJjU