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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 4 |
| 4 | 3 |
| 5 | 48 |
| 6 | 10 |
| 7 | 1440 |
| 8 | 1890 |
| 9 | 85120 |
| 10 | 49896 |
| 11 | 7257600 |
| 12 | 6883800 |
| 13 | 958003200 |
| 14 | 792277200 |
| 15 | 178919989248 |
| 16 | 194107914000 |
| 17 | 41845579776000 |
| 18 | 29714949264000 |
| 19 | 12804747411456000 |
| 20 | 12900082757417856 |
| 21 | 4918792391884800000 |
| 22 | 4594737608304480000 |
| 23 | 2248001455555215360000 |
[1,0,4,3,48,10,1440,1890,85120,49896,7257600, 6883800,958003200,792277200,178919989248, 194107914000,41845579776000,29714949264000, 12804747411456000,12900082757417856, 4918792391884800000,4594737608304480000, 2248001455555215360000] |