Question 111
Given a $(2n + 1) \times (2n + 1)$ table, all its cells being white.
Per move it is allowed to change the color of any three consecutive cells in any row or in any column (white cell is replaced by black one and vice versa).
Find all possible values of $n$ such that one can obtain the chess coloring of the given table with black corner cells (the example of such coloring is shown in the figure for $n = 2$).
(E. Barabanov)
Per move it is allowed to change the color of any three consecutive cells in any row or in any column (white cell is replaced by black one and vice versa).
Find all possible values of $n$ such that one can obtain the chess coloring of the given table with black corner cells (the example of such coloring is shown in the figure for $n = 2$).
(E. Barabanov)