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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 28 |
| 2 | 3900 |
| 3 | 685216 |
| 4 | 133501500 |
| 5 | 27583083528 |
| 6 | 5919115212192 |
| 7 | 1304298034300800 |
| 8 | 293086491979934268 |
| 9 | 66857471357130883000 |
| 10 | 15434267149448839091400 |
| 11 | 3597756971630997935635200 |
| 12 | 845406187463509505329860000 |
| 13 | 200002748013094535687584437696 |
[1,28,3900,685216,133501500,27583083528, 5919115212192,1304298034300800,293086491979934268, 66857471357130883000,15434267149448839091400, 3597756971630997935635200, 845406187463509505329860000, 200002748013094535687584437696] |