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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 5 |
| 4 | 18 |
| 5 | 42 |
| 6 | 170 |
| 7 | 405 |
| 8 | 1769 |
| 9 | 4507 |
| 10 | 20081 |
| 11 | 53008 |
| 12 | 240428 |
| 13 | 652160 |
| 14 | 3002052 |
| 15 | 8299727 |
| 16 | 38570944 |
| 17 | 108387118 |
| 18 | 507729121 |
| 19 | 1444491686 |
| 20 | 6809942459 |
[1,3,5,18,42,170,405,1769,4507,20081,53008,240428, 652160,3002052,8299727,38570944,108387118, 507729121,1444491686,6809942459] |