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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 2 |
| 4 | 14 |
| 5 | 273 |
| 6 | 7855 |
| 7 | 311552 |
| 8 | 14895797 |
| 9 | 831959075 |
| 10 | 52959962415 |
[1,0,2,14,273,7855,311552,14895797,831959075, 52959962415] |