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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 18 |
| 5 | 181 |
| 6 | 2788 |
| 7 | 62590 |
| 8 | 1989540 |
| 9 | 87979661 |
| 10 | 5349559222 |
| 11 | 443306080232 |
| 12 | 49679250634068 |
| 13 | 7473835936432840 |
| 14 | 1498682325685621140 |
| 15 | 397803907069442925517 |
| 16 | 138847938093177059278212 |
| 17 | 63325340852730727078521540 |
| 18 | 37513306417359729218973719474 |
| 19 | 28701720575221087513434901774347 |
[1,1,3,18,181,2788,62590,1989540,87979661, 5349559222,443306080232,49679250634068, 7473835936432840,1498682325685621140, 397803907069442925517,138847938093177059278212, 63325340852730727078521540, 37513306417359729218973719474, 28701720575221087513434901774347] |