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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 70 |
| 3 | 34650 |
| 4 | 63063000 |
| 5 | 42251309100 |
| 6 | 17268436078740 |
| 7 | 6595449547140990 |
| 8 | 2941134289344290882 |
[1,1,70,34650,63063000,42251309100,17268436078740, 6595449547140990,2941134289344290882] |