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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 18 |
| 3 | 560 |
| 4 | 68614 |
| 5 | 34210752 |
| 6 | 69223161876 |
| 7 | 564393502852608 |
| 8 | 18462508476328312902 |
| 9 | 2418515748615522678533120 |
| 10 | 1267759405004680431879193624828 |
| 11 | 2658525712652053771685500828954042368 |
[1,2,18,560,68614,34210752,69223161876, 564393502852608,18462508476328312902, 2418515748615522678533120, 1267759405004680431879193624828, 2658525712652053771685500828954042368] |