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| n | a(n) |
|---|---|
| 1 | -1 |
| 2 | 0 |
| 3 | 2 |
| 4 | 62 |
| 5 | 554 |
| 6 | 74258 |
| 7 | 142682 |
| 8 | 2830946 |
| 9 | 1448977246 |
| 10 | 12576415426 |
| 11 | 1857881203154 |
| 12 | 64634117421826 |
| 13 | 62771945063582 |
| 14 | 164497840779865642 |
| 15 | 350742295126606034006 |
| 16 | 5774653629556529218142 |
| 17 | 5647762835059481932498 |
| 18 | 12720214895833193424471634 |
[-1,0,2,62,554,74258,142682,2830946,1448977246, 12576415426,1857881203154,64634117421826, 62771945063582,164497840779865642, 350742295126606034006,5774653629556529218142, 5647762835059481932498,12720214895833193424471634] |