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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 18 |
| 4 | 178 |
| 5 | 2565 |
| 6 | 50266 |
| 7 | 1281189 |
| 8 | 41079928 |
| 9 | 1614373833 |
| 10 | 76159289386 |
| 11 | 4240914224481 |
| 12 | 274875377524804 |
| 13 | 20493884997114945 |
| 14 | 1739962105428020566 |
| 15 | 166758905926021916373 |
| 16 | 17904330331671454817392 |
| 17 | 2139078334935145657604961 |
| 18 | 282684498251824376254841266 |
[1,1,3,18,178,2565,50266,1281189,41079928, 1614373833,76159289386,4240914224481, 274875377524804,20493884997114945, 1739962105428020566,166758905926021916373, 17904330331671454817392,2139078334935145657604961, 282684498251824376254841266] |