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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 37 |
| 4 | 193 |
| 5 | 1021 |
| 6 | 5383 |
| 7 | 28393 |
| 8 | 149761 |
| 9 | 789913 |
| 10 | 4166407 |
| 11 | 21975757 |
| 12 | 115911361 |
| 13 | 611375701 |
| 14 | 3224707591 |
| 15 | 17008754257 |
| 16 | 89712854017 |
| 17 | 473191396273 |
| 18 | 2495853018631 |
| 19 | 13164403113973 |
| 20 | 69435783298753 |
| 21 | 366239772557101 |
[1,7,37,193,1021,5383,28393,149761,789913,4166407, 21975757,115911361,611375701,3224707591, 17008754257,89712854017,473191396273, 2495853018631,13164403113973,69435783298753, 366239772557101] |