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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 21 |
| 4 | 87 |
| 5 | 317 |
| 6 | 1215 |
| 7 | 4565 |
| 8 | 17287 |
| 9 | 65261 |
| 10 | 246671 |
| 11 | 931909 |
| 12 | 3521367 |
| 13 | 13305053 |
| 14 | 50272991 |
| 15 | 189953717 |
| 16 | 717732903 |
| 17 | 2711921613 |
| 18 | 10246881583 |
| 19 | 38717399589 |
| 20 | 146292038647 |
[1,7,21,87,317,1215,4565,17287,65261,246671, 931909,3521367,13305053,50272991,189953717, 717732903,2711921613,10246881583,38717399589, 146292038647] |