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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 50 |
| 3 | 398 |
| 4 | 3186 |
| 5 | 25486 |
| 6 | 203890 |
| 7 | 1631118 |
| 8 | 13048946 |
| 9 | 104391566 |
| 10 | 835132530 |
| 11 | 6681060238 |
| 12 | 53448481906 |
| 13 | 427587855246 |
| 14 | 3420702841970 |
| 15 | 27365622735758 |
| 16 | 218924981886066 |
| 17 | 1751399855088526 |
| 18 | 14011198840708210 |
| 19 | 112089590725665678 |
| 20 | 896716725805325426 |
| 21 | 7173733806442603406 |
[1,6,50,398,3186,25486,203890,1631118,13048946, 104391566,835132530,6681060238,53448481906, 427587855246,3420702841970,27365622735758, 218924981886066,1751399855088526, 14011198840708210,112089590725665678, 896716725805325426,7173733806442603406] |