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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 18 |
| 3 | 354 |
| 4 | 7749 |
| 5 | 231799 |
| 6 | 8178855 |
| 7 | 318511707 |
| 8 | 13046748480 |
| 9 | 547969772934 |
| 10 | 23296216625352 |
| 11 | 996235422019600 |
| 12 | 42723792981743991 |
| 13 | 1834737810552367569 |
| 14 | 78843837462576032709 |
| 15 | 3389239985131275364833 |
| 16 | 145715407979704223557482 |
[4,18,354,7749,231799,8178855,318511707, 13046748480,547969772934,23296216625352, 996235422019600,42723792981743991, 1834737810552367569,78843837462576032709, 3389239985131275364833,145715407979704223557482] |