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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 12 |
| 3 | 72 |
| 4 | 9000 |
| 5 | 900 |
| 6 | 2469600 |
| 7 | 2116800 |
| 8 | 2268000 |
| 9 | 264600 |
| 10 | 93915360 |
| 11 | 42688800 |
| 12 | 537145408800 |
| 13 | 103297194000 |
| 14 | 18162144000 |
| 15 | 11416204800 |
| 16 | 294461024457600 |
| 17 | 2165154591600 |
| 18 | 75709937046744000 |
| 19 | 1859542313428800 |
| 20 | 6151869307584 |
[1,12,72,9000,900,2469600,2116800,2268000,264600, 93915360,42688800,537145408800,103297194000, 18162144000,11416204800,294461024457600, 2165154591600,75709937046744000,1859542313428800, 6151869307584] |