Time Well Spent

magic square

The Journal of Recreational Mathematics published this remarkable magic square, composed by “a puzzlist who at the time was a prison inmate.”

The large 13 x 13 square is magic — that is, each row and column adds to the same sum — but so is each successive nested square, from 11 x 11 down to 3 x 3.

The magic constant of each square is 10,874 smaller than the last.

And every cell is prime.