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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 8 |
| 2 | 63 |
| 3 | 497 |
| 4 | 3920 |
| 5 | 30919 |
| 6 | 243873 |
| 7 | 1923544 |
| 8 | 15171919 |
| 9 | 119668241 |
| 10 | 943881120 |
| 11 | 7444845527 |
| 12 | 58721086529 |
| 13 | 463161524392 |
| 14 | 3653178276447 |
| 15 | 28814378605873 |
| 16 | 227272898176240 |
| 17 | 1792610937474791 |
| 18 | 14139186849557217 |
| 19 | 111522584509224056 |
| 20 | 879632399511468911 |
| 21 | 6938084888144850769 |
[1,8,63,497,3920,30919,243873,1923544,15171919, 119668241,943881120,7444845527,58721086529, 463161524392,3653178276447,28814378605873, 227272898176240,1792610937474791, 14139186849557217,111522584509224056, 879632399511468911,6938084888144850769] |