A051631 as a triangular array
| | | | | | | | | | | -1 |
| | | | | | | | | | | 0 | | 0 |
| | | | | | | | | | 1 | | 0 | | 1 |
| | | | | | | | | 2 | | 1 | | 1 | | 2 |
| | | | | | | | 3 | | 3 | | 2 | | 3 | | 3 |
| | | | | | | 4 | | 6 | | 5 | | 5 | | 6 | | 4 |
| | | | | | 5 | | 10 | | 11 | | 10 | | 11 | | 10 | | 5 |
| | | | | 6 | | 15 | | 21 | | 21 | | 21 | | 21 | | 15 | | 6 |
| | | | 7 | | 21 | | 36 | | 42 | | 42 | | 42 | | 36 | | 21 | | 7 |
| | | 8 | | 28 | | 57 | | 78 | | 84 | | 84 | | 78 | | 57 | | 28 | | 8 |
| | 9 | | 36 | | 85 | | 135 | | 162 | | 168 | | 162 | | 135 | | 85 | | 36 | | 9 |
|
A051631 as a square array
| -1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
| | 0 | 0 | 1 | 3 | 6 | 10 | 15 | 21 | 28 | 36
| | 1 | 1 | 2 | 5 | 11 | 21 | 36 | 57 | 85
| | 2 | 3 | 5 | 10 | 21 | 42 | 78 | 135
| | 3 | 6 | 11 | 21 | 42 | 84 | 162
| | 4 | 10 | 21 | 42 | 84 | 168
| | 5 | 15 | 36 | 78 | 162
| | 6 | 21 | 57 | 135
| | 7 | 28 | 85
| | 8 | 36
| | 9
|
A051631 as an upper right triangle
| -1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
| | 0 | 0 | 1 | 3 | 6 | 10 | 15 | 21 | 28 | 36
| | | 1 | 1 | 2 | 5 | 11 | 21 | 36 | 57 | 85
| | | | 2 | 3 | 5 | 10 | 21 | 42 | 78 | 135
| | | | | 3 | 6 | 11 | 21 | 42 | 84 | 162
| | | | | | 4 | 10 | 21 | 42 | 84 | 168
| | | | | | | 5 | 15 | 36 | 78 | 162
| | | | | | | | 6 | 21 | 57 | 135
| | | | | | | | | 7 | 28 | 85
| | | | | | | | | | 8 | 36
| | | | | | | | | | | 9
|
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