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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 3 |
| 5 | 24 |
| 6 | 70 |
| 7 | 720 |
| 8 | 4305 |
| 9 | 39200 |
| 10 | 337176 |
| 11 | 3628800 |
| 12 | 38417610 |
| 13 | 479001600 |
| 14 | 6128488080 |
| 15 | 87104969952 |
| 16 | 1297383162075 |
| 17 | 20922789888000 |
| 18 | 354250929192160 |
| 19 | 6402373705728000 |
| 20 | 121407227453840328 |
| 21 | 2432849766865689600 |
| 22 | 51041047393559059200 |
| 23 | 1124000727777607680000 |
[0,1,2,3,24,70,720,4305,39200,337176,3628800, 38417610,479001600,6128488080,87104969952, 1297383162075,20922789888000,354250929192160, 6402373705728000,121407227453840328, 2432849766865689600,51041047393559059200, 1124000727777607680000] |