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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 5 |
| 3 | 38 |
| 4 | 390 |
| 5 | 5049 |
| 6 | 78960 |
| 7 | 1447886 |
| 8 | 30461872 |
| 9 | 723267369 |
| 10 | 19130274880 |
| 11 | 557794986814 |
| 12 | 17775137850624 |
| 13 | 614607897664305 |
| 14 | 22917282895782912 |
| 15 | 916671255921364950 |
| 16 | 39152092883971954688 |
| 17 | 1778431981539189344177 |
| 18 | 85607684151779322519552 |
| 19 | 4353142694568849287025142 |
| 20 | 233169669255877689516032000 |
[0,1,5,38,390,5049,78960,1447886,30461872, 723267369,19130274880,557794986814,17775137850624, 614607897664305,22917282895782912, 916671255921364950,39152092883971954688, 1778431981539189344177,85607684151779322519552, 4353142694568849287025142, 233169669255877689516032000] |