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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 12 |
| 5 | 304 |
| 6 | 44976 |
| 7 | 51871384 |
| 8 | 600608922384 |
| 9 | 87357442179208880 |
| 10 | 194354337721367202187520 |
[1,1,2,12,304,44976,51871384,600608922384, 87357442179208880,194354337721367202187520] |