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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 12 |
| 2 | 48 |
| 3 | 252 |
| 4 | 1440 |
| 5 | 8544 |
| 6 | 52416 |
| 7 | 330588 |
| 8 | 2130240 |
| 9 | 13961808 |
| 10 | 92784384 |
| 11 | 623772288 |
| 12 | 4234688640 |
| 13 | 28990262016 |
| 14 | 199908428544 |
| 15 | 1387276513308 |
| 16 | 9681052037760 |
| 17 | 67895140257840 |
| 18 | 478281284627328 |
| 19 | 3382695596455344 |
[1,12,48,252,1440,8544,52416,330588,2130240, 13961808,92784384,623772288,4234688640, 28990262016,199908428544,1387276513308, 9681052037760,67895140257840,478281284627328, 3382695596455344] |