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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 5 |
| 3 | 60 |
| 4 | 1140 |
| 5 | 29640 |
| 6 | 978120 |
| 7 | 39124800 |
| 8 | 1838865600 |
| 9 | 99298742400 |
| 10 | 6057223286400 |
| 11 | 411891183475200 |
| 12 | 30891838760640000 |
| 13 | 2533130778372480000 |
| 14 | 225448639275150720000 |
| 15 | 21643069370414469120000 |
| 16 | 2229236145152690319360000 |
| 17 | 245215975966795935129600000 |
| 18 | 28690269188115124410163200000 |
[1,5,60,1140,29640,978120,39124800,1838865600, 99298742400,6057223286400,411891183475200, 30891838760640000,2533130778372480000, 225448639275150720000,21643069370414469120000, 2229236145152690319360000, 245215975966795935129600000, 28690269188115124410163200000] |