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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 8 |
| 3 | 56 |
| 4 | 624 |
| 5 | 9536 |
| 6 | 184480 |
| 7 | 4313088 |
| 8 | 118183744 |
| 9 | 3712870400 |
| 10 | 131536027008 |
| 11 | 5187183672320 |
| 12 | 225342288987904 |
| 13 | 10691937463283712 |
| 14 | 550121848577067520 |
| 15 | 30507449271343837184 |
| 16 | 1813943300823318205440 |
| 17 | 115116132876009362358272 |
[0,2,8,56,624,9536,184480,4313088,118183744, 3712870400,131536027008,5187183672320, 225342288987904,10691937463283712, 550121848577067520,30507449271343837184, 1813943300823318205440,115116132876009362358272] |