Triangle begins:
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n| k 1 2 3 4 5 6 7 8 9 10
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1| 1;
2| 1, 3;
3| 2, 3, 4;
4| 3, 6, 4, 7;
5| 5, 9, 8, 7, 6;
6| 7, 15, 12, 14, 6, 12;
7| 11, 21, 20, 21, 12, 12, 8;
8| 15, 33, 28, 35, 18, 24, 8, 15;
9| 22, 45, 44, 49, 30, 36, 16, 15, 13;
10| 30, 66, 60, 77, 42, 60, 24, 30, 13, 18;
...
The sum of row 10 is [30 + 66 + 60 + 77 + 42 + 60 + 24 + 30 + 13 + 18] =
A066186(10) = 420.
.
For n = 10 the calculation of the row 10 is as follows:
1 1 * 30 = 30
2 3 * 22 = 66
3 4 * 15 = 60
4 7 * 11 = 77
5 6 * 7 = 42
6 12 * 5 = 60
7 8 * 3 = 24
8 15 * 2 = 30
9 13 * 1 = 13
10 18 * 1 = 18
.
For n = 10 we can see below three views of two associated polycubes called here "prism of partitions" and "tower". Both objects contain the same number of cubes (that property is valid for n >= 1).
_ _ _ _ _ _ _ _ _ _
42 |_ _ _ _ _ |
|_ _ _ _ _|_ |
|_ _ _ _ _ _|_ |
|_ _ _ _ | |
|_ _ _ _|_ _ _|_ |
|_ _ _ _ | |
|_ _ _ _|_ | |
|_ _ _ _ _|_ | |
|_ _ _ | | |
|_ _ _|_ | | |
|_ _ | | | |
|_ _|_ _|_ _|_ _|_ | _
30 |_ _ _ _ _ | | | | 30
|_ _ _ _ _|_ | | | |
|_ _ _ | | | | |
|_ _ _|_ _ _|_ | | | |
|_ _ _ _ | | | | |
|_ _ _ _|_ | | | | |
|_ _ _ | | | | | |
|_ _ _|_ _|_ _|_ | | _|_|
22 |_ _ _ _ | | | | | 22
|_ _ _ _|_ | | | | |
|_ _ _ _ _|_ | | | | |
|_ _ _ | | | | | |
|_ _ _|_ | | | | | |
|_ _ | | | | | | |
|_ _|_ _|_ _|_ | | | _|_ _|
15 |_ _ _ _ | | | | | | | 15
|_ _ _ _|_ | | | | | | |
|_ _ _ | | | | | | | |
|_ _ _|_ _|_ | | | | _|_|_ _|
11 |_ _ _ | | | | | | | | 11
|_ _ _|_ | | | | | | | |
|_ _ | | | | | | | | |
|_ _|_ _|_ | | | | | _| |_ _ _|
7 |_ _ _ | | | | | | | | | 7
|_ _ _|_ | | | | | | _|_ _|_ _ _|
5 |_ _ | | | | | | | | | | | 5
|_ _|_ | | | | | | | _| | |_ _ _ _|
3 |_ _ | | | | | | | | _|_ _|_|_ _ _ _| 3
2 |_ | | | | | | | | | _ _|_ _|_|_ _ _ _ _| 2
1 |_|_|_|_|_|_|_|_|_|_| |_ _|_|_|_ _ _ _ _ _| 1
.
Figure 1. Figure 2.
Front view of the Lateral view
prism of partitions. of the tower.
.
. _ _ _ _ _ _ _ _ _ _
| | | | | | | | |_| 1
| | | | | | |_|_ _| 2
| | | | |_|_ |_ _| 3
| | |_|_ |_ _ _| 4
| |_ _ |_ |_ _ _| 5
|_ _ |_ |_ _ _ _| 6
|_ | |_ _ _ _| 7
|_ |_ _ _ _ _| 8
| | 9
|_ _ _ _ _ _| 10
.
Figure 3.
Top view
of the tower.
.
Figure 1 is a two-dimensional diagram of the partitions of 10 in colexicographic order (cf.
A026792,
A211992). The area of the diagram is 10*42 =
A066186(10) = 420. Note that the diagram can be interpreted also as the front view of a right prism whose volume is 1*10*42 = 420 equaling the volume and the number of cubes of the tower that appears in the figures 2 and 3.
Note that the shape and the area of the lateral view of the tower are the same as the shape and the area where the 1's are located in the diagram of partitions. In this case the mentioned area equals
A000070(10-1) = 97.
The connection between these two associated objects is a representation of the correspondence divisor/part described in
A338156. See also
A336812.
The sum of the volumes of both objects equals
A220909.
