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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 27 |
| 5 | 175 |
| 6 | 1523 |
| 7 | 16744 |
| 8 | 222792 |
| 9 | 3482889 |
| 10 | 62611360 |
| 11 | 1273388483 |
| 12 | 28925945020 |
| 13 | 726303053021 |
| 14 | 19985519004484 |
| 15 | 598321182418026 |
| 16 | 19368155278585653 |
| 17 | 674303663351809096 |
| 18 | 25130986416486383799 |
[1,1,2,6,27,175,1523,16744,222792,3482889, 62611360,1273388483,28925945020,726303053021, 19985519004484,598321182418026,19368155278585653, 674303663351809096,25130986416486383799] |