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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 3 |
| 2 | 16 |
| 3 | 81 |
| 4 | 392 |
| 5 | 1815 |
| 6 | 8112 |
| 7 | 35301 |
| 8 | 150544 |
| 9 | 632043 |
| 10 | 2620880 |
| 11 | 10759353 |
[0,3,16,81,392,1815,8112,35301,150544,632043, 2620880,10759353] |