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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 15 |
| 4 | 105 |
| 5 | 945 |
| 6 | 10395 |
| 7 | 135135 |
| 8 | 2027025 |
| 9 | 34459425 |
| 10 | 654729075 |
| 11 | 13749310575 |
| 12 | 316234143225 |
| 13 | 7905853580625 |
| 14 | 213458046676875 |
| 15 | 6190283353629375 |
| 16 | 191898783962510625 |
| 17 | 6332659870762850625 |
| 18 | 221643095476699771875 |
| 19 | 8200794532637891559375 |
| 20 | 319830986772877770815625 |
[1,1,3,15,105,945,10395,135135,2027025,34459425, 654729075,13749310575,316234143225,7905853580625, 213458046676875,6190283353629375, 191898783962510625,6332659870762850625, 221643095476699771875,8200794532637891559375, 319830986772877770815625] |