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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 21 |
| 2 | 1689 |
| 3 | 6761 |
| 4 | 432753 |
| 5 | 216380469 |
| 6 | 17310490881 |
| 7 | 346210001661 |
| 8 | 88629768707061 |
| 9 | 70903816147601 |
| 10 | 709038163609433721 |
| 11 | 14180763279964210461 |
| 12 | 4537844250045576077041 |
| 13 | 18151377000520343309289 |
[1,21,1689,6761,432753,216380469,17310490881, 346210001661,88629768707061,70903816147601, 709038163609433721,14180763279964210461, 4537844250045576077041,18151377000520343309289] |