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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 14 |
| 4 | 84 |
| 5 | 634 |
| 6 | 5740 |
| 7 | 60626 |
| 8 | 731852 |
| 9 | 9938670 |
| 10 | 149966116 |
| 11 | 2489148386 |
| 12 | 45070961740 |
| 13 | 884107377360 |
| 14 | 18676602726734 |
| 15 | 422721143355808 |
| 16 | 10205605681874952 |
| 17 | 261789688633794528 |
| 18 | 7110331886095458918 |
| 19 | 203848868169846041430 |
| 20 | 6151813078359073154568 |
[1,1,3,14,84,634,5740,60626,731852,9938670, 149966116,2489148386,45070961740,884107377360, 18676602726734,422721143355808,10205605681874952, 261789688633794528,7110331886095458918, 203848868169846041430,6151813078359073154568] |