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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 56 |
| 5 | 284 |
| 6 | 1526 |
| 7 | 8530 |
| 8 | 49106 |
| 9 | 289149 |
| 10 | 1733347 |
| 11 | 10542987 |
| 12 | 64904203 |
| 13 | 403632551 |
| 14 | 2531971729 |
| 15 | 16002136283 |
| 16 | 101795589297 |
| 17 | 651286316903 |
| 18 | 4188174878517 |
| 19 | 27055199929042 |
| 20 | 175488689467350 |
| 21 | 1142479579205721 |
| 22 | 7462785088260791 |
| 23 | 48896570201100002 |
[0,1,3,12,56,284,1526,8530,49106,289149,1733347, 10542987,64904203,403632551,2531971729, 16002136283,101795589297,651286316903, 4188174878517,27055199929042,175488689467350, 1142479579205721,7462785088260791, 48896570201100002] |