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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 16 |
| 3 | 351 |
| 4 | 26278 |
| 5 | 6316836 |
| 6 | 4769336288 |
| 7 | 11598374165583 |
| 8 | 90071290640636405 |
| 9 | 2231818836473290517838 |
[2,16,351,26278,6316836,4769336288,11598374165583, 90071290640636405,2231818836473290517838] |