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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 54 |
| 5 | 290 |
| 6 | 1674 |
| 7 | 10857 |
| 8 | 76398 |
| 9 | 580230 |
| 10 | 4706734 |
| 11 | 40598349 |
| 12 | 370694845 |
| 13 | 3569027696 |
| 14 | 36100349833 |
| 15 | 382360758863 |
| 16 | 4228730647420 |
| 17 | 48716663849192 |
| 18 | 583403253712747 |
| 19 | 7248883337962522 |
| 20 | 93291181556742684 |
| 21 | 1241632098163126324 |
| 22 | 17064777292709034968 |
| 23 | 241874821482784132204 |
[1,1,3,13,54,290,1674,10857,76398,580230,4706734, 40598349,370694845,3569027696,36100349833, 382360758863,4228730647420,48716663849192, 583403253712747,7248883337962522, 93291181556742684,1241632098163126324, 17064777292709034968,241874821482784132204] |