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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 21 |
| 3 | 1485 |
| 4 | 225225 |
| 5 | 59520825 |
| 6 | 24325703325 |
| 7 | 14230536445125 |
| 8 | 11288163762500625 |
| 9 | 11665426077721040625 |
| 10 | 15230046989184655753125 |
| 11 | 24515740420894935215128125 |
| 12 | 47702727710977364941596305625 |
[1,1,21,1485,225225,59520825,24325703325, 14230536445125,11288163762500625, 11665426077721040625,15230046989184655753125, 24515740420894935215128125, 47702727710977364941596305625] |