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Magic rectangles
What are magic rectangles?
A 2-dimensional magic rectangle of order (m1, m2) is defined as an m1 x m2 rectangular array in which all rows of the array sum to the same value (called the row constant or the row sum) and all columns of the array also do (the column constant or the column sum). It is not required that diagonals be magic. An order-(m1, m2) magic rectangle is called normal if the rectangle consists of consecutive integers from 1 to m1m2, and called non-normal if not. This site is concerned only with normal magic rectangles. Similarly, n-dimensional magic rectangles are defined.
The following figures are examples of associated 2-dimensional magic rectangles:
(3,5)-rectangle
(associated)
| 14 | 10 | 4 | 5 | 7 |
| 1 | 3 | 8 | 13 | 15 |
| 9 | 11 | 12 | 6 | 2 |
(3,7)-rectangle
(associated)
| 10 | 21 | 9 | 16 | 5 | 14 | 2 |
| 3 | 4 | 7 | 11 | 15 | 18 | 19 |
| 20 | 8 | 17 | 6 | 13 | 1 | 12 |
(5,7)-rectangle
(associated)
| 26 | 19 | 8 | 31 | 25 | 13 | 4 |
| 20 | 6 | 34 | 24 | 14 | 1 | 27 |
| 3 | 7 | 15 | 18 | 21 | 29 | 33 |
| 9 | 35 | 22 | 12 | 2 | 30 | 16 |
| 32 | 23 | 11 | 5 | 28 | 17 | 10 |
Magic rectangles of (odd,odd)-order are used in order to construct magic cubes and magic tesseracts (see the pages for Nasik magic cubes and Nasik magic tesseracts). However, it is not easy to construct (odd,odd)-order magic rectangles algorithmically (discuss later). On the other hand, it is not so difficult to construct (even,even)-order magic rectangles (see the figure below). Normal magic rectangles of (odd,even)-order cannot exist.
(4,6)-rectangle
(non-associated)
| 1 | 2 | 3 | 22 | 23 | 24 |
| 19 | 20 | 21 | 4 | 5 | 6 |
| 18 | 17 | 16 | 9 | 8 | 7 |
| 12 | 11 | 10 | 15 | 14 | 13 |
Existence of magic rectangles
For m1, m2 > 1, an order-(m1, m2) 2-dimensional normal magic rectangle exists only if one of the following conditions is hold:
(1) Both m1 and m2 are even and at least one of them is greater than 2.
(2) Both m1 and m2 are odd.
T. Harmuth published a proof of this theorem in 1881. Thomas R. Hagedorn showed an elementary proof of the theorem with a concreat construction method in [2]. (The method is elementary but complicated.) He also proved the existence of the following magic rectangles in [1]:
(1) An order-(m1, m2, ..., mn) n-dimenaional magic rectangle, where m1, .., mn > 1 are even integers and (mi, mj) is not (2,2) for 1 <= i < j <= n,
(2) An order-(m1, m2, m3) 3-dimensional magic rectangle, where m1, m2, m3 > 1 are odd integers and gcd(m1, m2) > 1, where gcd means the greatest common divisor.
Furthermore, it can be proved the existence of the following magic rectangles by generalizing the Hagedorn's proof:
(2)' An order-(m1, m2, ..., mn) n-dimenaional magic rectangle, where m1, .., mn > 1 are odd integers and gcd(mi, mj) > 1 for some i and j such that1 <= i < j <= n.
As a result, 3-dimensional magic rectangles of orders (3,3,5), (3,3,7), (3,5,5), (3,5,9), (3,5,15), (3,7,15), etc. do exist. Hagedorn said in [1] that it was an open question whether an order-(3,5,7) 3-dimensional magic rectangle exists or not. I found an order-(3,5,7) 3-dimensional magic rectangle in April 2004, and an order-(3,5,11) and an order-(3,5,13) 3-dimensional magic rectangle in February 2005. I found these magic rectangles by searching by my personal computer (1.46GHz). It is unknown whether an order-(m1, m2, m3) 3-dimensional magic rectangle can exist or not for any odd m1, m2, m3 > 1.
Examples of 3-dimensional magic rectangles
an order-(3,3,5) 3-dimensional magic rectangle (associated)
Plane No.1
| 31 | 3 | 38 | 13 | 30 |
| 24 | 41 | 12 | 36 | 2 |
| 14 | 25 | 19 | 20 | 37 |
Plane No.2
| 29 | 40 | 4 | 35 | 7 |
| 1 | 18 | 23 | 28 | 45 |
| 39 | 11 | 42 | 6 | 17 |
Plane No.3
| 9 | 26 | 27 | 21 | 32 |
| 44 | 10 | 34 | 5 | 22 |
| 16 | 33 | 8 | 43 | 15 |
an order-(3,3,7) 3-dimensional magic rectangle (associated)
Plane No.1
| 33 | 4 | 37 | 11 | 30 | 33 | 34 |
| 35 | 23 | 32 | 36 | 13 | 31 | 12 |
| 10 | 51 | 9 | 31 | 35 | 14 | 32 |
Plane No.2
| 25 | 36 | 24 | 46 | 5 | 44 | 2 |
| 3 | 34 | 7 | 26 | 45 | 18 | 49 |
| 50 | 8 | 47 | 6 | 28 | 16 | 27 |
Plane No.3
| 20 | 38 | 17 | 21 | 43 | 1 | 42 |
| 40 | 21 | 39 | 16 | 20 | 29 | 17 |
| 18 | 19 | 22 | 41 | 15 | 48 | 19 |
an order-(3,5,7) 3-dimensional magic rectangle (associated) [Nakamura, April 2004]
Plane No.1
| 70 | 54 | 35 | 99 | 22 | 87 | 4 |
| 63 | 29 | 93 | 45 | 92 | 24 | 25 |
| 89 | 94 | 38 | 9 | 18 | 67 | 56 |
| 41 | 31 | 40 | 34 | 48 | 76 | 101 |
| 2 | 57 | 59 | 78 | 85 | 11 | 79 |
Plane No.2
| 62 | 10 | 103 | 32 | 90 | 23 | 51 |
| 91 | 100 | 8 | 42 | 1 | 60 | 69 |
| 20 | 26 | 33 | 53 | 73 | 80 | 86 |
| 37 | 46 | 105 | 64 | 98 | 6 | 15 |
| 55 | 83 | 16 | 74 | 3 | 96 | 44 |
Plane No.3
| 27 | 95 | 21 | 28 | 47 | 49 | 104 |
| 5 | 30 | 58 | 72 | 66 | 75 | 65 |
| 50 | 39 | 88 | 97 | 68 | 12 | 17 |
| 81 | 82 | 14 | 61 | 13 | 77 | 43 |
| 102 | 19 | 84 | 7 | 71 | 52 | 36 |
an order-(3,5,11) 3-dimensional magic rectangle (associated) [Nakamura, February 2005]
Plane No.1
| 51 | 28 | 120 | 79 | 145 | 44 | 124 | 75 | 5 | 109 | 133 |
| 101 | 152 | 20 | 50 | 13 | 130 | 96 | 110 | 128 | 106 | 7 |
| 119 | 62 | 67 | 17 | 151 | 24 | 126 | 90 | 78 | 31 | 148 |
| 49 | 141 | 131 | 164 | 22 | 158 | 3 | 1 | 64 | 150 | 30 |
| 95 | 32 | 77 | 105 | 84 | 59 | 66 | 139 | 140 | 19 | 97 |
Plane No.2
| 129 | 74 | 103 | 143 | 4 | 98 | 43 | 113 | 155 | 6 | 45 |
| 12 | 81 | 127 | 34 | 73 | 111 | 9 | 137 | 86 | 118 | 125 |
| 112 | 52 | 94 | 156 | 58 | 83 | 108 | 10 | 72 | 114 | 54 |
| 41 | 48 | 80 | 29 | 157 | 55 | 93 | 132 | 39 | 85 | 154 |
| 121 | 160 | 11 | 53 | 123 | 68 | 162 | 23 | 63 | 92 | 37 |
Plane No.3
| 69 | 147 | 26 | 27 | 100 | 107 | 82 | 61 | 89 | 134 | 71 |
| 136 | 16 | 102 | 165 | 163 | 8 | 144 | 2 | 35 | 25 | 117 |
| 18 | 135 | 88 | 76 | 40 | 142 | 15 | 149 | 99 | 104 | 47 |
| 159 | 60 | 38 | 56 | 70 | 36 | 153 | 116 | 146 | 14 | 65 |
| 33 | 57 | 161 | 91 | 42 | 122 | 21 | 87 | 46 | 138 | 115 |
an order-(3,5,13) 3-dimensional magic rectangle (associated) [Nakamura, February 2005]
Plane No.1
| 37 | 106 | 131 | 13 | 116 | 121 | 58 | 74 | 171 | 182 | 187 | 26 | 52 |
| 84 | 69 | 55 | 180 | 173 | 93 | 175 | 70 | 18 | 31 | 85 | 91 | 150 |
| 193 | 134 | 36 | 44 | 43 | 101 | 89 | 167 | 54 | 78 | 15 | 192 | 128 |
| 166 | 79 | 155 | 124 | 12 | 38 | 148 | 2 | 190 | 99 | 8 | 120 | 133 |
| 10 | 102 | 113 | 129 | 146 | 137 | 20 | 177 | 57 | 100 | 195 | 61 | 27 |
Plane No.2
| 88 | 53 | 162 | 185 | 39 | 154 | 60 | 161 | 73 | 45 | 24 | 174 | 56 |
| 147 | 149 | 51 | 17 | 115 | 7 | 71 | 66 | 92 | 191 | 168 | 86 | 114 |
| 33 | 156 | 77 | 132 | 109 | 164 | 98 | 32 | 87 | 64 | 119 | 40 | 163 |
| 82 | 110 | 28 | 5 | 104 | 130 | 125 | 189 | 81 | 179 | 145 | 47 | 49 |
| 140 | 22 | 172 | 151 | 123 | 35 | 136 | 42 | 157 | 11 | 34 | 143 | 108 |
Plane No.3
| 169 | 135 | 1 | 96 | 139 | 19 | 176 | 59 | 50 | 67 | 83 | 94 | 186 |
| 63 | 76 | 188 | 97 | 6 | 194 | 48 | 158 | 184 | 72 | 41 | 117 | 30 |
| 68 | 4 | 181 | 118 | 142 | 29 | 107 | 95 | 153 | 152 | 160 | 62 | 3 |
| 46 | 105 | 111 | 165 | 178 | 126 | 21 | 103 | 23 | 16 | 141 | 127 | 112 |
| 144 | 170 | 9 | 14 | 25 | 122 | 138 | 75 | 80 | 183 | 65 | 90 | 159 |
References
[1] Thomas R. Hagedorn, On the existence of magic n-dimensional rectangles, Discrete Mathematics 207 (1999), 53-63.
[2] Thomas R. Hagedorn, Magic retangles revisited, Discrete Mathematics 207 (1999), 65-72.
[3] Marián Trenkler, Magic rectangles, The Mathematical Gazette 83(1999), 102-105.
[4] Harvey D. Heinz & John R. Hendricks, Magic Square Lexicon: Illustrated, self-published, 2000, ISBN 0-9687985-0-0.
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This page was last updated on October 1, 2007.
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