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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 3600 |
| 4 | 101250 |
| 5 | 1308960 |
| 6 | 10627200 |
| 7 | 62596800 |
| 8 | 290984400 |
| 9 | 1127417600 |
| 10 | 3784631040 |
| 11 | 11325193200 |
| 12 | 30820816800 |
| 13 | 77376189600 |
| 14 | 181349280000 |
| 15 | 400953775680 |
| 16 | 842626285650 |
| 17 | 1692061228800 |
| 18 | 3263458752000 |
[1,0,0,3600,101250,1308960,10627200,62596800, 290984400,1127417600,3784631040,11325193200, 30820816800,77376189600,181349280000,400953775680, 842626285650,1692061228800,3263458752000] |