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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 5 |
| 3 | 55 |
| 4 | 220 |
| 5 | 2420 |
| 6 | 79860 |
| 7 | 878460 |
| 8 | 28989180 |
| 9 | 956642940 |
| 10 | 32525859960 |
| 11 | 1073353378680 |
| 12 | 35420661496440 |
| 13 | 1168881829382520 |
| 14 | 38573100369623160 |
| 15 | 1234339211827941120 |
| 16 | 40733193990322056960 |
| 17 | 4154785787012849809920 |
[1,5,55,220,2420,79860,878460,28989180,956642940, 32525859960,1073353378680,35420661496440, 1168881829382520,38573100369623160, 1234339211827941120,40733193990322056960, 4154785787012849809920] |