Question 110
The plane is divided into equilateral triangles with side length 1. Consider an equilateral triangle with side length $n$ whose sides lie on the grid lines. There is a stone on each grid point on the edge and inside this triangle. In one turn, a standard triangle is selected, which has a stone on exactly 2 corners. The two stones are removed and a new stone is placed on the third corner. For which $n$ is it possible that after a finite number of moves only one stone remains?