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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 2 |
| 5 | 6 |
| 6 | 24 |
| 7 | 48 |
| 8 | 720 |
| 9 | 720 |
| 10 | 1440 |
| 11 | 241920 |
| 12 | 120960 |
| 13 | 3628800 |
| 14 | 14515200 |
| 15 | 87091200 |
| 16 | 958003200 |
| 17 | 261273600 |
| 18 | 2615348736000 |
| 19 | 804722688000 |
| 20 | 125536739328000 |
| 21 | 2414168064000 |
| 22 | 753220435968000 |
| 23 | 256094948229120000 |
| 24 | 22596613079040000 |
| 25 | 102181884343418880000 |
[1,1,2,2,6,24,48,720,720,1440,241920,120960, 3628800,14515200,87091200,958003200,261273600, 2615348736000,804722688000,125536739328000, 2414168064000,753220435968000,256094948229120000, 22596613079040000,102181884343418880000] |