The OP did leave a comment below the question with some motivation:
by n=3 is IMO 1996shortlist. so I think General n have this . Do not know to have who has this information or Paper? artofproblemsolving.com/Forum/… –
So, it seems this is a generalization of another problem from the International Math Olympiad.
In the end, I think it's better to think of votes as a sort of stochastic process: better questions will have higher vote counts on average, but there is also a lot of variance, so sometimes the vote count will not seem to match the question.
Still, there are several factors that could have applied here:
- The question is not trivial. Many PSQs are.
- The OP has reasonable reputation. Many PSQs are asked by very new users.
- The OP had stated (in the comment) a plausible source and motivation. The statement is not at all thorough, but it is not entirely absent, either.
- Different people see different questions (this is part of the randomness of voting)