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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 4 |
| 4 | 52 |
| 5 | 674 |
| 6 | 38238 |
| 7 | 2284728 |
| 8 | 620488671 |
| 9 | 174162198742 |
| 10 | 206752746752932 |
[1,0,4,52,674,38238,2284728,620488671, 174162198742,206752746752932] |