If you are interested in learning Skat, here are the rules: Skat Rules
Before the game starts, there is some bidding to be done. Based on their cards, everyone has a number in their head to which they can agree. Then the bidding starts. One player says 18; the other player says yes or pass. If yes, then the first player says either pass or 20. These are the numbers used:
You start with the number 18, 20, 22, ..., 264.
Here is how the numbers are created (a German overview): Skat Numbers Overview
I need your help to create an equation that generates those numbers. Where do I start?