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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 8 |
| 2 | 168 |
| 3 | 5840 |
| 4 | 261800 |
| 5 | 13180608 |
| 6 | 702273264 |
| 7 | 38641656768 |
| 8 | 2171652448680 |
| 9 | 123938999632448 |
| 10 | 7158206751686848 |
| 11 | 417418594698260064 |
| 12 | 24535017440445455216 |
| 13 | 1451786144317963971200 |
| 14 | 86396682439552099487040 |
| 15 | 5166936574734171792925440 |
| 16 | 310340697572034456203934120 |
[1,8,168,5840,261800,13180608,702273264, 38641656768,2171652448680,123938999632448, 7158206751686848,417418594698260064, 24535017440445455216,1451786144317963971200, 86396682439552099487040,5166936574734171792925440, 310340697572034456203934120] |