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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 8 |
| 3 | 56 |
| 4 | 524 |
| 5 | 5979 |
| 6 | 85539 |
| 7 | 1460752 |
| 8 | 29112516 |
| 9 | 661843866 |
| 10 | 16890042828 |
| 11 | 477756925128 |
| 12 | 14830113520286 |
| 13 | 501073056287725 |
| 14 | 18303233207719437 |
| 15 | 718663995114727640 |
| 16 | 30181996254384621880 |
| 17 | 1349979517537576728657 |
| 18 | 64065538251202398110415 |
| 19 | 3215056386968174418054634 |
[1,1,8,56,524,5979,85539,1460752,29112516, 661843866,16890042828,477756925128,14830113520286, 501073056287725,18303233207719437, 718663995114727640,30181996254384621880, 1349979517537576728657,64065538251202398110415, 3215056386968174418054634] |