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| n | a(n) |
|---|---|
| 3 | 1 |
| 4 | 1 |
| 5 | 2 |
| 6 | 7 |
| 7 | 25 |
| 8 | 118 |
| 9 | 558 |
| 10 | 2876 |
| 11 | 14982 |
| 12 | 80075 |
| 13 | 431889 |
| 14 | 2354991 |
| 15 | 12930257 |
| 16 | 71459124 |
| 17 | 396978189 |
| 18 | 2215609864 |
[1,1,2,7,25,118,558,2876,14982,80075,431889, 2354991,12930257,71459124,396978189,2215609864] |