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| n | a(n) |
|---|---|
| 2 | 4 |
| 3 | 12 |
| 4 | 880 |
| 5 | 46900 |
| 6 | 1615824 |
| 7 | 45094896 |
| 8 | 1115345088 |
| 9 | 25519125060 |
| 10 | 553014576400 |
| 11 | 11514200107696 |
| 12 | 232490008680384 |
| 13 | 4581732884262352 |
| 14 | 88532684825838400 |
| 15 | 1683073282734360000 |
| 16 | 31561148509363526400 |
| 17 | 584964180982546208100 |
[4,12,880,46900,1615824,45094896,1115345088, 25519125060,553014576400,11514200107696, 232490008680384,4581732884262352, 88532684825838400,1683073282734360000, 31561148509363526400,584964180982546208100] |