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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 7 |
| 2 | 12 |
| 3 | 71 |
| 4 | 308 |
| 5 | 1752 |
| 6 | 9518 |
| 7 | 55995 |
| 8 | 331024 |
| 9 | 2018056 |
| 10 | 12445114 |
| 11 | 77971468 |
| 12 | 493457274 |
| 13 | 3154471374 |
| 14 | 20324817414 |
| 15 | 131901428431 |
| 16 | 861253742060 |
| 17 | 5654523909972 |
| 18 | 37304630338790 |
| 19 | 247183333507140 |
| 20 | 1644269062695294 |
[1,7,12,71,308,1752,9518,55995,331024,2018056, 12445114,77971468,493457274,3154471374, 20324817414,131901428431,861253742060, 5654523909972,37304630338790,247183333507140, 1644269062695294] |