You
must post a (auto)translated version! My spider sense tell me I'll get like 30 points here. (Obviously, I can't guarantee that, only 1 upvote.) I guess even some interesting comments, and perhaps a solution.
I read it. (I studied German in Primary School. I don't remember too much, but enough to skim the texts in Norwegian.) I'm also mathematician, so it's the kind of stuff I like. My guess is modulo 9 and then some bounds should explain most of it, but life is never so easy.
If you post the (auto)tranlated version and nobody gives an answer, I promise to try to solve it. (Obviously, I can't guarantee a solution.)
(In my experience, autotranlations does 90% of the job, but you need to polish it a little and in particular ensure the technical words are the correct ones.)
