+51 An 8 by 8 checkerboard has alternating black and white squares. How many distinct squares, with sides on the grid lines of the checkerboard (horizontal and vertical) and containing at least 4 black squares, can be drawn on the checkerboard?
https://latex.artofproblemsolving.com/8/7/a/87aa3c21435405d11d99ede53e0abc0dac7f4963.png
