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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 24 |
| 6 | 120 |
| 7 | 720 |
| 8 | 3465 |
| 9 | 18480 |
| 10 | 194040 |
| 11 | 2293200 |
| 12 | 19219200 |
| 13 | 301593600 |
| 14 | 1163962800 |
| 15 | 6518191680 |
| 16 | 20078358300 |
| 17 | 548021073600 |
| 18 | 42643458457600 |
| 19 | 1090774779494400 |
| 20 | 15198128594288640 |
| 21 | 136285012131840000 |
| 22 | 55135902013920000 |
| 23 | 1951331488666560000 |
| 24 | 9736473836722913280000 |
[1,1,2,6,24,120,720,3465,18480,194040,2293200, 19219200,301593600,1163962800,6518191680, 20078358300,548021073600,42643458457600, 1090774779494400,15198128594288640, 136285012131840000,55135902013920000, 1951331488666560000,9736473836722913280000] |