Q: Three squares, five squares, seven squares, nine squares, twenty-five squares and eighty-one squares!

Write 1 in the middle of the first line, then move down to the bottom, move one space to the right and write down 2, and finally write it to the upper right.

Then pan to the far left, move up one space and write in the upper right corner. When you meet a number, write down a space and continue to write to the right.

According to this rule, you can write any odd square grid.