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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | -2 |
| 4 | -64 |
| 5 | -238 |
| 6 | 1024 |
| 7 | 18478 |
| 8 | 64256 |
| 9 | -1078558 |
| 10 | -16672256 |
| 11 | -22614242 |
| 12 | 2401458176 |
| 13 | 32373060722 |
| 14 | -117093134336 |
| 15 | -9756500186162 |
| 16 | -106877784162304 |
| 17 | 1553450981649602 |
| 18 | 64518260702838784 |
| 19 | 465844716994278718 |
[1,2,4,-2,-64,-238,1024,18478,64256,-1078558, -16672256,-22614242,2401458176,32373060722, -117093134336,-9756500186162,-106877784162304, 1553450981649602,64518260702838784, 465844716994278718] |