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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 9 |
| 3 | 18 |
| 4 | 42 |
| 5 | 165 |
| 6 | 317 |
| 7 | 559 |
| 8 | 634 |
| 9 | 2604 |
| 10 | 7421 |
| 11 | 9401 |
| 12 | 20760 |
| 13 | 86376 |
| 14 | 178008 |
| 15 | 3549196 |
| 16 | 3840921 |
| 17 | 5633768 |
| 18 | 16454380 |
| 19 | 28751054 |
[1,9,18,42,165,317,559,634,2604,7421,9401,20760, 86376,178008,3549196,3840921,5633768,16454380, 28751054] |