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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 21 |
| 2 | 245 |
| 3 | 2325 |
| 4 | 20181 |
| 5 | 168021 |
| 6 | 1370965 |
| 7 | 11075925 |
| 8 | 89042261 |
| 9 | 714081621 |
| 10 | 5719635285 |
| 11 | 45785027925 |
| 12 | 366392038741 |
| 13 | 2931583636821 |
| 14 | 23454458533205 |
| 15 | 187642826282325 |
| 16 | 1501171242849621 |
| 17 | 12009484474209621 |
| 18 | 96076333921424725 |
| 19 | 768612503886583125 |
| 20 | 6148907361161794901 |
[1,21,245,2325,20181,168021,1370965,11075925, 89042261,714081621,5719635285,45785027925, 366392038741,2931583636821,23454458533205, 187642826282325,1501171242849621, 12009484474209621,96076333921424725, 768612503886583125,6148907361161794901] |