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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 30 |
| 5 | 104 |
| 6 | 390 |
| 7 | 1518 |
| 8 | 6208 |
| 9 | 26372 |
| 10 | 116221 |
| 11 | 529341 |
| 12 | 2487054 |
| 13 | 12027502 |
| 14 | 59778867 |
| 15 | 304916272 |
| 16 | 1594273763 |
| 17 | 8535706749 |
| 18 | 46753269749 |
| 19 | 261771468438 |
| 20 | 1497087288210 |
| 21 | 8739579074131 |
| 22 | 52045067963540 |
| 23 | 315980654042243 |
| 24 | 1954770128712348 |
| 25 | 12315770916526091 |
[1,1,3,9,30,104,390,1518,6208,26372,116221,529341, 2487054,12027502,59778867,304916272,1594273763, 8535706749,46753269749,261771468438,1497087288210, 8739579074131,52045067963540,315980654042243, 1954770128712348,12315770916526091] |