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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 6 |
| 4 | 6 |
| 5 | 120 |
| 6 | 360 |
| 7 | 5040 |
| 8 | 2520 |
| 9 | 72576 |
| 10 | 1814400 |
| 11 | 39916800 |
| 12 | 59875200 |
| 13 | 1245404160 |
| 14 | 21794572800 |
| 15 | 1307674368000 |
| 16 | 81729648000 |
| 17 | 71137485619200 |
| 18 | 3201186852864000 |
| 19 | 121645100408832000 |
| 20 | 12164510040883200 |
| 21 | 10218188434341888000 |
| 22 | 281000181944401920000 |
| 23 | 25852016738884976640000 |
[1,1,6,6,120,360,5040,2520,72576,1814400,39916800, 59875200,1245404160,21794572800,1307674368000, 81729648000,71137485619200,3201186852864000, 121645100408832000,12164510040883200, 10218188434341888000,281000181944401920000, 25852016738884976640000] |