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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 12 |
| 5 | 30 |
| 6 | 180 |
| 7 | 395780 |
| 8 | 56 |
| 9 | 5339880 |
| 10 | 18448242120 |
| 11 | 1192281609186360 |
| 12 | 180180 |
| 13 | 393869810468558572779517216129800 |
| 14 | 2914872400440 |
| 15 | 2914872400440 |
| 16 | 180026486640 |
| 17 | 4193048661254917704240 |
| 18 | 2640766128 |
| 19 | 11832093494672880 |
[1,2,3,12,30,180,395780,56,5339880,18448242120, 1192281609186360,180180, 393869810468558572779517216129800,2914872400440, 2914872400440,180026486640,4193048661254917704240, 2640766128,11832093494672880] |