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| n | a(n) |
|---|---|
| 3 | 1 |
| 4 | 18 |
| 5 | 215 |
| 6 | 2475 |
| 7 | 28294 |
| 8 | 340116 |
| 9 | 4335596 |
| 10 | 57773700 |
| 11 | 831170736 |
| 12 | 12532005288 |
| 13 | 201002619168 |
| 14 | 3401283910752 |
| 15 | 60929911689984 |
| 16 | 1143429812726400 |
| 17 | 22572470529457920 |
| 18 | 468013463441475840 |
| 19 | 10124124979606179840 |
[1,18,215,2475,28294,340116,4335596,57773700, 831170736,12532005288,201002619168,3401283910752, 60929911689984,1143429812726400,22572470529457920, 468013463441475840,10124124979606179840] |