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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 21 |
| 2 | 308 |
| 3 | 3942 |
| 4 | 47271 |
| 5 | 547407 |
| 6 | 6213586 |
| 7 | 69694464 |
| 8 | 776054741 |
| 9 | 8602512633 |
| 10 | 95089014384 |
| 11 | 1049208790266 |
| 12 | 11563904125411 |
| 13 | 127361197423299 |
| 14 | 1402080935995502 |
| 15 | 15430644646390548 |
| 16 | 169791371563507281 |
| 17 | 1868085050371321005 |
| 18 | 20551595296294241740 |
| 19 | 226086166454705682510 |
| 20 | 2487078158370047768351 |
[1,21,308,3942,47271,547407,6213586,69694464, 776054741,8602512633,95089014384,1049208790266, 11563904125411,127361197423299,1402080935995502, 15430644646390548,169791371563507281, 1868085050371321005,20551595296294241740, 226086166454705682510,2487078158370047768351] |