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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 15 |
| 3 | 1551 |
| 4 | 13575355 |
| 5 | 584728215424 |
| 6 | 1568091719977974635 |
| 7 | 8230385298024619110939311 |
| 8 | 2126394147054521999411737472214659 |
| 9 | 1020701618427502395624813185662022237910866 |
[1,15,1551,13575355,584728215424, 1568091719977974635,8230385298024619110939311, 2126394147054521999411737472214659, 1020701618427502395624813185662022237910866] |