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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 144 |
| 6 | 2880 |
| 7 | 2073600 |
| 8 | 1306368000 |
| 9 | 17557585920000 |
| 10 | 637129677864960000 |
| 11 | 2312016175036366848000000 |
| 12 | 640890883720080890265600000000 |
| 13 | 306987758727332698566646824960000000000 |
| 14 | 136544225638605874463902854662848512000000000000 |
[1,1,2,6,144,2880,2073600,1306368000, 17557585920000,637129677864960000, 2312016175036366848000000, 640890883720080890265600000000, 306987758727332698566646824960000000000, 136544225638605874463902854662848512000000000000] |