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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 21 |
| 5 | 65 |
| 6 | 267 |
| 7 | 804 |
| 8 | 2530 |
| 9 | 9407 |
| 10 | 29876 |
| 11 | 96530 |
| 12 | 337607 |
| 13 | 1100968 |
| 14 | 3612017 |
| 15 | 12284181 |
| 16 | 40538721 |
| 17 | 133971666 |
| 18 | 450045654 |
| 19 | 1492504271 |
| 20 | 4949649998 |
| 21 | 16537407509 |
| 22 | 54951656907 |
| 23 | 182545459254 |
| 24 | 608458757050 |
| 25 | 2023395434235 |
| 26 | 6727009100372 |
| 27 | 22399013790607 |
[1,1,2,8,21,65,267,804,2530,9407,29876,96530, 337607,1100968,3612017,12284181,40538721, 133971666,450045654,1492504271,4949649998, 16537407509,54951656907,182545459254,608458757050, 2023395434235,6727009100372,22399013790607] |