MathDB

Starting with a

5 \times 5

grid, choose a

4 \times 4

square in it. Then, choose a

3 \times 3

square in the

4 \times 4

square, and a

2 \times 2

square in the

3 \times 3

square, and a

1 \times 1

square in the

2 \times 2

square. Assuming all squares chosen are made of unit squares inside the grid. In how many ways can the squares be chosen so that the final

1 \times 1

square is the center of the original

5 \times 5

grid?
Proposed by Nancy Kuang

Problem Statement