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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 6 |
| 3 | 210 |
| 4 | 7140 |
| 5 | 242556 |
| 6 | 8239770 |
| 7 | 279909630 |
| 8 | 9508687656 |
| 9 | 323015470680 |
[0,6,210,7140,242556,8239770,279909630,9508687656, 323015470680] |