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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 1 |
| 4 | 21 |
| 5 | -122 |
| 6 | 1752 |
| 7 | -21730 |
| 8 | 309166 |
| 9 | -4521032 |
| 10 | 70344768 |
| 11 | -1173530712 |
| 12 | 21642745704 |
| 13 | -448130571696 |
| 14 | 10352684535840 |
| 15 | -260101132095888 |
| 16 | 6921279885508848 |
| 17 | -191813249398678272 |
| 18 | 5502934340821289088 |
| 19 | -163695952380982280832 |
| 20 | 5078687529186002247552 |
[1,2,1,21,-122,1752,-21730,309166,-4521032, 70344768,-1173530712,21642745704,-448130571696, 10352684535840,-260101132095888,6921279885508848, -191813249398678272,5502934340821289088, -163695952380982280832,5078687529186002247552] |