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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | -1 |
| 3 | 4 |
| 4 | -6 |
| 5 | 8 |
| 6 | -90 |
| 7 | 152 |
| 8 | 6440 |
| 9 | -69984 |
| 10 | 451080 |
| 11 | -4819168 |
| 12 | 67077648 |
| 13 | -533622208 |
| 14 | 882593712 |
| 15 | 16010702528 |
| 16 | -325947073920 |
| 17 | 15149145074176 |
| 18 | -402497641556352 |
| 19 | 6097893929134592 |
| 20 | -75930618112953600 |
| 21 | 1338998058465717248 |
| 22 | -21267088125132503808 |
[0,0,-1,4,-6,8,-90,152,6440,-69984,451080, -4819168,67077648,-533622208,882593712, 16010702528,-325947073920,15149145074176, -402497641556352,6097893929134592, -75930618112953600,1338998058465717248, -21267088125132503808] |