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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 3 |
| 6 | 6 |
| 7 | 5 |
| 8 | 360 |
| 9 | 420 |
| 10 | 56 |
| 11 | 756 |
| 12 | 75600 |
| 13 | 415800 |
| 14 | 2494800 |
| 15 | 8424 |
| 16 | 1223040 |
| 17 | 504504000 |
| 18 | 9081072000 |
| 19 | 5145940800 |
| 20 | 111152321280 |
| 21 | 754247894400 |
| 22 | 37712394720000 |
| 23 | 430747632000 |
| 24 | 14454741869568 |
| 25 | 319672175961600 |
| 26 | 4080179409546240 |
| 27 | 14011605115200000 |
| 28 | 1653814216454400000 |
[1,1,1,2,3,6,5,360,420,56,756,75600,415800, 2494800,8424,1223040,504504000,9081072000, 5145940800,111152321280,754247894400, 37712394720000,430747632000,14454741869568, 319672175961600,4080179409546240, 14011605115200000,1653814216454400000] |