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| n | a(n) |
|---|---|
| 6 | 1 |
| 7 | 42 |
| 8 | 1128 |
| 9 | 24804 |
| 10 | 487635 |
| 11 | 8936928 |
| 12 | 156238908 |
| 13 | 2641902120 |
| 14 | 43595145594 |
| 15 | 706252528630 |
| 16 | 11279926456656 |
| 17 | 178152655364880 |
| 18 | 2788629694000605 |
| 19 | 43334780015908584 |
| 20 | 669413654240461560 |
| 21 | 10289781864706066800 |
[1,42,1128,24804,487635,8936928,156238908, 2641902120,43595145594,706252528630, 11279926456656,178152655364880,2788629694000605, 43334780015908584,669413654240461560, 10289781864706066800] |