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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 27 |
| 3 | 74 |
| 4 | 287 |
| 5 | 1307 |
| 6 | 4491 |
| 7 | 17828 |
| 8 | 80293 |
| 9 | 304958 |
| 10 | 1254491 |
| 11 | 5534905 |
| 12 | 22489246 |
| 13 | 94732609 |
| 14 | 413955598 |
| 15 | 1740468900 |
| 16 | 7436093945 |
| 17 | 32346857005 |
| 18 | 138259463124 |
| 19 | 595133929409 |
| 20 | 2583681234015 |
| 21 | 11128738383880 |
| 22 | 48080514602454 |
[3,27,74,287,1307,4491,17828,80293,304958,1254491, 5534905,22489246,94732609,413955598,1740468900, 7436093945,32346857005,138259463124,595133929409, 2583681234015,11128738383880,48080514602454] |