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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 9 |
| 2 | 49 |
| 3 | 281 |
| 4 | 1633 |
| 5 | 9513 |
| 6 | 55441 |
| 7 | 323129 |
| 8 | 1883329 |
| 9 | 10976841 |
| 10 | 63977713 |
| 11 | 372889433 |
| 12 | 2173358881 |
| 13 | 12667263849 |
| 14 | 73830224209 |
| 15 | 430314081401 |
| 16 | 2508054264193 |
| 17 | 14618011503753 |
| 18 | 85200014758321 |
| 19 | 496582077046169 |
| 20 | 2894292447518689 |
| 21 | 16869172608065961 |
| 22 | 98320743200877073 |
[1,9,49,281,1633,9513,55441,323129,1883329, 10976841,63977713,372889433,2173358881, 12667263849,73830224209,430314081401, 2508054264193,14618011503753,85200014758321, 496582077046169,2894292447518689, 16869172608065961,98320743200877073] |