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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 85 |
| 5 | 780 |
| 6 | 9331 |
| 7 | 134512 |
| 8 | 2306025 |
| 9 | 45433800 |
| 10 | 1018872811 |
| 11 | 25506741084 |
| 12 | 707972099627 |
| 13 | 21518492021208 |
| 14 | 712601187601395 |
| 15 | 25491847538274240 |
| 16 | 981272544393935569 |
| 17 | 40392787067756440272 |
| 18 | 1772592132899627652691 |
[1,1,3,12,85,780,9331,134512,2306025,45433800, 1018872811,25506741084,707972099627, 21518492021208,712601187601395,25491847538274240, 981272544393935569,40392787067756440272, 1772592132899627652691] |