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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 1 |
| 4 | 6 |
| 5 | 4 |
| 6 | 1 |
| 7 | 24 |
| 8 | 216 |
| 9 | 16 |
| 10 | 1 |
| 11 | 120 |
| 12 | 331776 |
| 13 | 10077696 |
| 14 | 256 |
| 15 | 1 |
| 16 | 720 |
| 17 | 24883200000 |
| 18 | 12116574790945106558976 |
| 19 | 1023490369077469249536 |
| 20 | 65536 |
| 21 | 1 |
[1,2,1,6,4,1,24,216,16,1,120,331776,10077696,256, 1,720,24883200000,12116574790945106558976, 1023490369077469249536,65536,1] |