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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | -9 |
| 3 | 6 |
| 4 | 36 |
| 5 | 150 |
| 6 | 540 |
| 7 | 1806 |
| 8 | 5796 |
| 9 | 18150 |
| 10 | 55980 |
| 11 | 171006 |
| 12 | 519156 |
| 13 | 1569750 |
| 14 | 4733820 |
| 15 | 14250606 |
| 16 | 42850116 |
| 17 | 128746950 |
| 18 | 386634060 |
| 19 | 1160688606 |
| 20 | 3483638676 |
| 21 | 10454061750 |
| 22 | 31368476700 |
| 23 | 94118013006 |
| 24 | 282379204836 |
| 25 | 847187946150 |
| 26 | 2541664501740 |
| 27 | 7625194831806 |
[3,-9,6,36,150,540,1806,5796,18150,55980,171006, 519156,1569750,4733820,14250606,42850116, 128746950,386634060,1160688606,3483638676, 10454061750,31368476700,94118013006,282379204836, 847187946150,2541664501740,7625194831806] |