See also the following two illustrations. It contains 1353 squares. Count the magic squares of order 5. There are about 320 million, not counting rotations and reflections. F skips the value 6, and probably 18.
Players alternate placing pentominos on the board.
Pentominos must not overlap. The last player to place a pentomino wins. See following illustration, for example. Find the number of domino coverings for various objects. See Applied Comb.