MathDB

The plane is divided into equilateral triangles of side length

1

. Consider a equilateral triangle of side length

n

whose sides lie on the grid lines. On every grid point on the edge and inside of this triangle lies a stone. In a move, a unit triangle is selected, which has exactly

2

corners with is covered with a stone. The two stones are removed, and the third corner is turned a new stone was laid. For which

n

is it possible that after finitely many moves only one stone left?

Problem Statement