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| n | a(n) |
|---|---|
| 1 | 81 |
| 2 | 345 |
| 3 | 1497 |
| 4 | 6663 |
| 5 | 29617 |
| 6 | 132471 |
| 7 | 592001 |
| 8 | 2651151 |
| 9 | 11872153 |
| 10 | 53217175 |
| 11 | 238621713 |
| 12 | 1070656959 |
| 13 | 4805940169 |
| 14 | 21584396967 |
| 15 | 96984517953 |
| 16 | 435991819343 |
| 17 | 1960896534009 |
| 18 | 8823336533943 |
| 19 | 39719697816561 |
| 20 | 178884059892959 |
[81,345,1497,6663,29617,132471,592001,2651151, 11872153,53217175,238621713,1070656959,4805940169, 21584396967,96984517953,435991819343, 1960896534009,8823336533943,39719697816561, 178884059892959] |