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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 57 |
| 3 | 481 |
| 4 | 3969 |
| 5 | 31741 |
| 6 | 253877 |
| 7 | 2030789 |
| 8 | 16245185 |
| 9 | 129954437 |
| 10 | 1039580065 |
| 11 | 8316201565 |
| 12 | 66526095969 |
| 13 | 532180632797 |
| 14 | 4257219986565 |
| 15 | 34055959366549 |
| 16 | 272433271491721 |
| 17 | 2179350950489929 |
| 18 | 17433885881159533 |
| 19 | 139463713657055833 |
[1,57,481,3969,31741,253877,2030789,16245185, 129954437,1039580065,8316201565,66526095969, 532180632797,4257219986565,34055959366549, 272433271491721,2179350950489929, 17433885881159533,139463713657055833] |