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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 3 |
| 5 | 12 |
| 6 | 20 |
| 7 | 300 |
| 8 | 525 |
| 9 | 1960 |
| 10 | 49392 |
| 11 | 1481760 |
| 12 | 5821200 |
| 13 | 164656800 |
| 14 | 336370320 |
| 15 | 3741185448 |
[1,1,2,3,12,20,300,525,1960,49392,1481760,5821200, 164656800,336370320,3741185448] |