Some no or low upvoted posts I think they don't deserve that:
- https://math.stackexchange.com/questions/1897738/largest-subset-with-no-arithmetic-progresssions/2361496#2361496
- https://math.stackexchange.com/questions/2379182/connected-multigraph-with-degree-sequence-1-4-9-16
Most upvoted answers/questions: