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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 120 |
| 6 | 40320 |
| 7 | 6227020800 |
| 8 | 51090942171709440000 |
| 9 | 295232799039604140847618609643520000000 |
| 10 | 12696403353658275925965100847566516959580321051449436762275840000000000000 |
[1,1,2,6,120,40320,6227020800, 51090942171709440000, 295232799039604140847618609643520000000, 12696403353658275925965100847566516959580321051449\ 436762275840000000000000] |