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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 12 |
| 4 | 120 |
| 5 | 1440 |
| 6 | 20880 |
| 7 | 352800 |
| 8 | 6814080 |
| 9 | 148055040 |
| 10 | 3574368000 |
| 11 | 94922150400 |
| 12 | 2749948185600 |
| 13 | 86306508288000 |
| 14 | 2917072801843200 |
| 15 | 105636550795776000 |
| 16 | 4080467097907200000 |
| 17 | 167469023145295872000 |
[1,0,2,12,120,1440,20880,352800,6814080,148055040, 3574368000,94922150400,2749948185600, 86306508288000,2917072801843200, 105636550795776000,4080467097907200000, 167469023145295872000] |