Nov 22
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13x13 magic square. Each nested square (11x11,9x9…to 3x3) is also magic, with a magic constant 10,874 smaller than its parent. Oh, and every cell is prime. (via fc)

13x13 magic square. Each nested square (11x11,9x9…to 3x3) is also magic, with a magic constant 10,874 smaller than its parent. Oh, and every cell is prime. (via fc)