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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 15 |
| 3 | 69 |
| 4 | 409 |
| 5 | 2447 |
| 6 | 16337 |
| 7 | 117959 |
| 8 | 880623 |
| 9 | 6849011 |
| 10 | 54825357 |
| 11 | 448752095 |
| 12 | 3741170439 |
| 13 | 31669329743 |
| 14 | 271560643329 |
| 15 | 2354418484607 |
| 16 | 20608371394595 |
| 17 | 181897678706317 |
| 18 | 1617351777154871 |
[3,15,69,409,2447,16337,117959,880623,6849011, 54825357,448752095,3741170439,31669329743, 271560643329,2354418484607,20608371394595, 181897678706317,1617351777154871] |