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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 14 |
| 3 | 100 |
| 4 | 1140 |
| 5 | 14880 |
| 6 | 249280 |
| 7 | 4801280 |
| 8 | 108574400 |
| 9 | 2767072000 |
| 10 | 79286592000 |
| 11 | 2508856627200 |
| 12 | 87115395136000 |
| 13 | 3287694620672000 |
| 14 | 134073047499776000 |
| 15 | 5872147278807040000 |
| 16 | 274939690654024704000 |
| 17 | 13701683362561818624000 |
| 18 | 724128149433185136640000 |
[1,2,14,100,1140,14880,249280,4801280,108574400, 2767072000,79286592000,2508856627200, 87115395136000,3287694620672000, 134073047499776000,5872147278807040000, 274939690654024704000,13701683362561818624000, 724128149433185136640000] |