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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 16 |
| 5 | 50 |
| 6 | 162 |
| 7 | 544 |
| 8 | 1870 |
| 9 | 6551 |
| 10 | 23310 |
| 11 | 84016 |
| 12 | 306104 |
| 13 | 1125550 |
| 14 | 4171522 |
| 15 | 15567213 |
| 16 | 58445096 |
| 17 | 220598990 |
| 18 | 836611770 |
| 19 | 3186364485 |
| 20 | 12182475716 |
| 21 | 46739872301 |
| 22 | 179893583304 |
| 23 | 694387330970 |
| 24 | 2687461451664 |
| 25 | 10426671725451 |
| 26 | 40544434121062 |
| 27 | 157989000668093 |
[1,1,2,5,16,50,162,544,1870,6551,23310,84016, 306104,1125550,4171522,15567213,58445096, 220598990,836611770,3186364485,12182475716, 46739872301,179893583304,694387330970, 2687461451664,10426671725451,40544434121062, 157989000668093] |