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| n | a(n) |
|---|---|
| 4 | 1 |
| 5 | 13 |
| 6 | 37 |
| 7 | 73 |
| 8 | 333 |
| 9 | 3889 |
| 10 | 39159 |
| 11 | 271617 |
| 12 | 3012146 |
| 13 | 61623325 |
| 14 | 1541710905 |
| 15 | 35611299121 |
| 16 | 1059291769629 |
| 17 | 47181801621713 |
| 18 | 2749984961944969 |
[1,13,37,73,333,3889,39159,271617,3012146, 61623325,1541710905,35611299121,1059291769629, 47181801621713,2749984961944969] |