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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 26 |
| 5 | 220 |
| 6 | 4692 |
| 7 | 163297 |
| 8 | 13125877 |
| 9 | 1146051177 |
| 10 | 213068838812 |
[0,1,1,26,220,4692,163297,13125877,1146051177, 213068838812] |