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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 16 |
| 5 | 53 |
| 6 | 194 |
| 7 | 678 |
| 8 | 2540 |
| 9 | 9864 |
| 10 | 39339 |
| 11 | 159002 |
| 12 | 650824 |
| 13 | 2696290 |
| 14 | 11362478 |
| 15 | 48339341 |
| 16 | 207535853 |
| 17 | 897905427 |
| 18 | 3913431910 |
| 19 | 17176437470 |
| 20 | 75847364805 |
| 21 | 336777968274 |
| 22 | 1503202127905 |
| 23 | 6739922000073 |
| 24 | 30346283721419 |
| 25 | 137170213293591 |
| 26 | 622379744415404 |
| 27 | 2833871341615016 |
| 28 | 12943682517721161 |
[1,1,2,5,16,53,194,678,2540,9864,39339,159002, 650824,2696290,11362478,48339341,207535853, 897905427,3913431910,17176437470,75847364805, 336777968274,1503202127905,6739922000073, 30346283721419,137170213293591,622379744415404, 2833871341615016,12943682517721161] |