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| n | a(n) |
|---|---|
| 2 | 2 |
| 3 | 12 |
| 4 | 84 |
| 5 | 780 |
| 6 | 9330 |
| 7 | 137256 |
| 8 | 2396744 |
| 9 | 48427560 |
| 10 | 1111111110 |
| 11 | 28531167060 |
| 12 | 810554586204 |
| 13 | 25239592216020 |
| 14 | 854769755812154 |
| 15 | 31278135027204240 |
| 16 | 1229782938247303440 |
| 17 | 51702516367896047760 |
| 18 | 2314494592664502210318 |
| 19 | 109912203092239643840220 |
[2,12,84,780,9330,137256,2396744,48427560, 1111111110,28531167060,810554586204, 25239592216020,854769755812154,31278135027204240, 1229782938247303440,51702516367896047760, 2314494592664502210318,109912203092239643840220] |