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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 11 |
| 5 | 51 |
| 6 | 162 |
| 7 | 876 |
| 8 | 3761 |
| 9 | 20782 |
| 10 | 109293 |
| 11 | 678569 |
| 12 | 4038388 |
| 13 | 27644436 |
| 14 | 186524145 |
| 15 | 1379760895 |
| 16 | 10323844183 |
| 17 | 82864869803 |
| 18 | 674798169662 |
| 19 | 5832742205056 |
| 20 | 51385856585637 |
| 21 | 474708148273586 |
| 22 | 4486977535287371 |
| 23 | 44152005855084345 |
| 24 | 444577220573083896 |
[1,1,1,4,11,51,162,876,3761,20782,109293,678569, 4038388,27644436,186524145,1379760895,10323844183, 82864869803,674798169662,5832742205056, 51385856585637,474708148273586,4486977535287371, 44152005855084345,444577220573083896] |