|Ultramagic Squares of Order 7|
|6 · (1,920,790 + 1,444,324) =|
On these pages you will find many details about transposing and calculating
ultramagic order-7 squares.|
These squares are pandiagonal and center symmetrical (associative).
(x,y) is the cell in column x and row y of the square, with x, y from 1 to 7.
n(x,y) is the natural number (from 1 to 49) in cell (x,y).
There are a = 1,920,790 squares with n(1,1) = 1 and n(2,1) < n(1,2).|
There are b = 1,444,324 squares with n(2,1) = 1 and n(1,1) < n(4,6).
This makes 2a squares with n(1,1) = 1 and 2b squares with n(2,1) = 1.
There are special transpositions that move the number 1 from (1,1) to 23 other cells|
without disturbing the special properties of the square.
Additionally the number 1 could be transposed from (2,1) to 23 new cells.
This makes 24 · (2a + 2b) squares.|
As it is not usual to count rotated and reflected squares, you have to devide by 8 and get:
24 · (2a + 2b) / 8 = 6 · (1,920,790 + 1,444,324) = 20,190,684
In 2004 Francis Gaspalou (France) told me about another transposition for ultramagic squares.|
It enables him to decrease the number of essentially different squares by the factor 2.
The numbers a und b were calculated by a small computer-program.|
The cells of the square were filled with numbers from -24 to 24.
Only 24 cells had to be inspected.
There are 12 equations connecting the numbers of these cells.
I saved all (a + b) = 3,365,114 essentially different squares on disk.|
This data can be used for further investigations.
First examinations of the data show that they contain 576 regular pan-magic squares.|
Thus there are 6 · 576 = 3456 regular ultramagic squares.
This is exactly what the theory predicts.
Notice that each of the 20,190,684 squares generates 49 panmagic squares.|
Thus you get a lower bound for the total number of panmagic squares:
(20,190,684 - 3456) · 49 + 38,102,400 = 1,027,276,572
(38,102,400 is the wellknown total of regular pan-magic 7x7-squares.)
But this is very weak, as there are more than 1017 pan-magic order-7 squares. (See conclusions)