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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 22 |
| 5 | 78 |
| 6 | 273 |
| 7 | 984 |
| 8 | 3573 |
| 9 | 13138 |
| 10 | 48670 |
| 11 | 181625 |
| 12 | 681630 |
| 13 | 2570979 |
| 14 | 9738171 |
| 15 | 37021873 |
| 16 | 141199583 |
| 17 | 540058408 |
| 18 | 2070814185 |
| 19 | 7958280782 |
| 20 | 30646175351 |
| 21 | 118230058466 |
| 22 | 456879024997 |
| 23 | 1768206394844 |
| 24 | 6852795439360 |
| 25 | 26592367534410 |
[1,1,2,7,22,78,273,984,3573,13138,48670,181625, 681630,2570979,9738171,37021873,141199583, 540058408,2070814185,7958280782,30646175351, 118230058466,456879024997,1768206394844, 6852795439360,26592367534410] |