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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 6 |
| 3 | 30 |
| 4 | 210 |
| 5 | 210 |
| 6 | 630 |
| 7 | 4410 |
| 8 | 39690 |
| 9 | 238140 |
| 10 | 4286520 |
| 11 | 12859560 |
| 12 | 270050760 |
| 13 | 1080203040 |
| 14 | 12962436480 |
| 15 | 362948221440 |
| 16 | 5444223321600 |
| 17 | 244990049472000 |
| 18 | 1469940296832000 |
| 19 | 61737492466944000 |
| 20 | 432162447268608000 |
| 21 | 9075411392640768000 |
| 22 | 571750917736368384000 |
[2,6,30,210,210,630,4410,39690,238140,4286520, 12859560,270050760,1080203040,12962436480, 362948221440,5444223321600,244990049472000, 1469940296832000,61737492466944000, 432162447268608000,9075411392640768000, 571750917736368384000] |