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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 75 |
| 5 | 561 |
| 6 | 5355 |
| 7 | 63405 |
| 8 | 894915 |
| 9 | 14511105 |
| 10 | 263544435 |
| 11 | 5284255725 |
| 12 | 116065424475 |
| 13 | 2778006733425 |
| 14 | 72093290744475 |
| 15 | 2017526711525325 |
| 16 | 60547198550713875 |
| 17 | 1938662110170410625 |
| 18 | 65941564342927147875 |
| 19 | 2374177441960545346125 |
| 20 | 90211614359319635056875 |
[1,3,13,75,561,5355,63405,894915,14511105, 263544435,5284255725,116065424475,2778006733425, 72093290744475,2017526711525325,60547198550713875, 1938662110170410625,65941564342927147875, 2374177441960545346125,90211614359319635056875] |