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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 16 |
| 3 | 144 |
| 4 | 2048 |
| 5 | 46400 |
| 6 | 1262592 |
| 7 | 44493568 |
| 8 | 2000420864 |
| 9 | 110023308288 |
[2,16,144,2048,46400,1262592,44493568,2000420864, 110023308288] |