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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 6 |
| 5 | 45 |
| 6 | 189 |
| 7 | 3402 |
| 8 | 30618 |
| 9 | 1299078 |
| 10 | 25332021 |
| 11 | 2507870079 |
| 12 | 106698472452 |
| 13 | 24487299427734 |
| 14 | 2283997201168644 |
| 15 | 1209640056157393380 |
| 16 | 248218139523497121576 |
| 17 | 302358334494179897593596 |
| 18 | 136861610819571430116630660 |
[1,1,3,6,45,189,3402,30618,1299078,25332021, 2507870079,106698472452,24487299427734, 2283997201168644,1209640056157393380, 248218139523497121576,302358334494179897593596, 136861610819571430116630660] |