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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 19 |
| 4 | 67 |
| 5 | 245 |
| 6 | 943 |
| 7 | 3733 |
| 8 | 15148 |
| 9 | 62691 |
| 10 | 263890 |
| 11 | 1125435 |
| 12 | 4858228 |
| 13 | 21183643 |
| 14 | 93173701 |
| 15 | 413028526 |
| 16 | 1843540504 |
| 17 | 8278392131 |
| 18 | 37380361777 |
| 19 | 169626259309 |
| 20 | 773179620400 |
| 21 | 3538786648904 |
| 22 | 16257620999050 |
| 23 | 74945848144070 |
| 24 | 346593310562478 |
| 25 | 1607561199422829 |
| 26 | 7476414123371464 |
| 27 | 34859423858670421 |
[1,2,6,19,67,245,943,3733,15148,62691,263890, 1125435,4858228,21183643,93173701,413028526, 1843540504,8278392131,37380361777,169626259309, 773179620400,3538786648904,16257620999050, 74945848144070,346593310562478,1607561199422829, 7476414123371464,34859423858670421] |