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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 9 |
| 3 | 18 |
| 4 | 38 |
| 5 | 98 |
| 6 | 384 |
| 7 | 2580 |
| 8 | 2580 |
| 9 | 2580 |
| 10 | 2580 |
| 11 | 2580 |
| 12 | 367574 |
| 13 | 721449 |
| 14 | 3879720 |
| 15 | 3879720 |
| 16 | 53671968 |
| 17 | 53671968 |
| 18 | 223610114 |
[1,9,18,38,98,384,2580,2580,2580,2580,2580,367574, 721449,3879720,3879720,53671968,53671968, 223610114] |