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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | -1 |
| 3 | -3 |
| 4 | -3 |
| 5 | 3 |
| 6 | 27 |
| 7 | 117 |
| 8 | 513 |
| 9 | 2655 |
| 10 | 16623 |
| 11 | 123057 |
| 12 | 1047717 |
| 13 | 10048203 |
| 14 | 106958115 |
| 15 | 1249780653 |
| 16 | 15892557417 |
| 17 | 218391870807 |
| 18 | 3224096456823 |
| 19 | 50878586091465 |
| 20 | 854556716966733 |
| 21 | 15219005900538627 |
| 22 | 286434426954471147 |
| 23 | 5680304836232044293 |
| 24 | 118378714577152138065 |
[1,1,-1,-3,-3,3,27,117,513,2655,16623,123057, 1047717,10048203,106958115,1249780653,15892557417, 218391870807,3224096456823,50878586091465, 854556716966733,15219005900538627, 286434426954471147,5680304836232044293, 118378714577152138065] |