Solution: 9 4 6 15 7 14 12 1 16 5 3 10 2 11 13 8 Not only a magic square, this is a Graeco-Latin square, with 4*A + B + 1: A B 2 0 1 3 0 3 1 2 1 3 2 0 2 1 3 0 3 1 0 2 3 0 2 1 0 2 3 1 1 2 0 3 Christian. -----Message d'origine----- De : math-fun-bounces@mailman.xmission.com [mailto:math-fun-bounces@mailman.xmission.com] De la part de Ed Pegg Jr Envoyé : dimanche 7 septembre 2008 21:07 À : math-fun Objet : [math-fun] A t-design that forces a magic square. It's easy to make a square with numbers 1-16 in order. .1 .2 .3 .4 | .9 .4 .. .. .5 .6 .7 .8 | .. .. .. .. .9 10 11 12 | .. .. .. .. 13 14 15 16 | .. .. .. .. Add a second square, so that for any pair of numbers 1 to 16, the chosen pair will be in a row, column, or main diagonal in exactly one of the two squares. The first row starts 9, then 4. What is this square? Hint: it's a magic square. Ed Pegg Jr _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun