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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 0 |
| 8 | 0 |
| 9 | 40320 |
| 10 | 403200 |
| 11 | 2217600 |
| 12 | 26611200 |
| 13 | 259459200 |
| 14 | 1695133440 |
| 15 | 16345929600 |
| 16 | 161902540800 |
| 17 | 1208560953600 |
| 18 | 50830132953600 |
| 19 | 866513503215360 |
| 20 | 8470676211379200 |
| 21 | 166891791625977600 |
| 22 | 2699606616475507200 |
[0,0,0,0,0,0,0,0,40320,403200,2217600,26611200, 259459200,1695133440,16345929600,161902540800, 1208560953600,50830132953600,866513503215360, 8470676211379200,166891791625977600, 2699606616475507200] |