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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 15 |
| 4 | 118 |
| 5 | 1410 |
| 6 | 30190 |
| 7 | 1180218 |
| 8 | 81842153 |
| 9 | 10130408182 |
| 10 | 2211726542134 |
[1,4,15,118,1410,30190,1180218,81842153, 10130408182,2211726542134] |