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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 10 |
| 3 | 64 |
| 4 | 498 |
| 5 | 4544 |
| 6 | 47272 |
| 7 | 549448 |
| 8 | 7032338 |
| 9 | 98034816 |
| 10 | 1475781592 |
| 11 | 23821854808 |
| 12 | 409932257560 |
| 13 | 7483462406840 |
| 14 | 144320890075608 |
| 15 | 2929683071286416 |
| 16 | 62402858556637970 |
| 17 | 1390821290318306688 |
| 18 | 32355429437927804952 |
| 19 | 783919832399050511928 |
| 20 | 19741529222451177258920 |
| 21 | 515813862624032150918280 |
[1,2,10,64,498,4544,47272,549448,7032338,98034816, 1475781592,23821854808,409932257560,7483462406840, 144320890075608,2929683071286416, 62402858556637970,1390821290318306688, 32355429437927804952,783919832399050511928, 19741529222451177258920,515813862624032150918280] |