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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 8 |
| 4 | 219 |
| 5 | 35980 |
| 6 | 19100497 |
| 7 | 39291988976 |
| 8 | 290849365371077 |
| 9 | 7804886774633048676 |
[0,1,8,219,35980,19100497,39291988976, 290849365371077,7804886774633048676] |