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| n | a(n) |
|---|---|
| 5 | 1 |
| 6 | 87 |
| 7 | 4320 |
| 8 | 176843 |
| 9 | 6768184 |
| 10 | 256059854 |
| 11 | 9846223168 |
| 12 | 390516805362 |
| 13 | 16102219296008 |
| 14 | 693122084961945 |
| 15 | 31208245366326896 |
| 16 | 1470819863019421317 |
| 17 | 72549461960461640120 |
| 18 | 3743176448672690767272 |
| 19 | 201836660477563528892704 |
| 20 | 11362223977488695430091444 |
[1,87,4320,176843,6768184,256059854,9846223168, 390516805362,16102219296008,693122084961945, 31208245366326896,1470819863019421317, 72549461960461640120,3743176448672690767272, 201836660477563528892704, 11362223977488695430091444] |