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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 12 |
| 3 | 72 |
| 4 | 720 |
| 5 | 10800 |
| 6 | 259200 |
| 7 | 10368000 |
| 8 | 673920000 |
| 9 | 70087680000 |
| 10 | 11774730240000 |
| 11 | 3214501355520000 |
| 12 | 1420809599139840000 |
| 13 | 1014458053785845760000 |
| 14 | 1171699052122651852800000 |
| 15 | 2191077227469358964736000000 |
[4,12,72,720,10800,259200,10368000,673920000, 70087680000,11774730240000,3214501355520000, 1420809599139840000,1014458053785845760000, 1171699052122651852800000, 2191077227469358964736000000] |