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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 2 |
| 5 | 4 |
| 6 | 135 |
| 7 | 2192 |
| 8 | 18140 |
| 9 | 96291 |
| 10 | 401459 |
| 11 | 1594603 |
| 12 | 7089502 |
| 13 | 45031108 |
| 14 | 518872408 |
| 15 | 7088206956 |
| 16 | 81255284697 |
| 17 | 741934496544 |
[1,1,2,2,4,135,2192,18140,96291,401459,1594603, 7089502,45031108,518872408,7088206956,81255284697, 741934496544] |