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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 10 |
| 3 | 88 |
| 4 | 1088 |
| 5 | 17296 |
| 6 | 336160 |
| 7 | 7722944 |
| 8 | 204747904 |
| 9 | 6152445568 |
| 10 | 206635255040 |
| 11 | 7670855683072 |
| 12 | 311892151155712 |
| 13 | 13784371218151424 |
| 14 | 657962006198824960 |
| 15 | 33732998333486350336 |
| 16 | 1848747736087419723776 |
| 17 | 107859057160535649206272 |
| 18 | 6674104727394168140922880 |
| 19 | 436582063054208216587501568 |
| 20 | 30102600290916367728363962368 |
| 21 | 2182043529056049327839246811136 |
[1,2,10,88,1088,17296,336160,7722944,204747904, 6152445568,206635255040,7670855683072, 311892151155712,13784371218151424, 657962006198824960,33732998333486350336, 1848747736087419723776,107859057160535649206272, 6674104727394168140922880, 436582063054208216587501568, 30102600290916367728363962368, 2182043529056049327839246811136] |