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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 8 |
| 5 | 63 |
| 6 | 866 |
| 7 | 18444 |
| 8 | 559083 |
| 9 | 22773527 |
| 10 | 1197061138 |
| 11 | 78782852673 |
| 12 | 6341384941543 |
| 13 | 612605031308910 |
| 14 | 69931195961966196 |
| 15 | 9310803519433216321 |
| 16 | 1429869869684956113511 |
| 17 | 250857267705012344767575 |
| 18 | 49858270430813771746874366 |
| 19 | 11143529422156562195864991584 |
[1,1,2,8,63,866,18444,559083,22773527,1197061138, 78782852673,6341384941543,612605031308910, 69931195961966196,9310803519433216321, 1429869869684956113511,250857267705012344767575, 49858270430813771746874366, 11143529422156562195864991584] |