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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 11 |
| 5 | 51 |
| 6 | 177 |
| 7 | 876 |
| 8 | 3965 |
| 9 | 20782 |
| 10 | 114462 |
| 11 | 678568 |
| 12 | 4160919 |
| 13 | 27640938 |
| 14 | 190402900 |
| 15 | 1378295071 |
| 16 | 10437144322 |
| 17 | 82285618466 |
| 18 | 671415306221 |
| 19 | 5676395537455 |
[1,2,4,11,51,177,876,3965,20782,114462,678568, 4160919,27640938,190402900,1378295071,10437144322, 82285618466,671415306221,5676395537455] |