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| n | a(n) |
|---|---|
| 1 | 21 |
| 2 | 56 |
| 3 | 997 |
| 4 | 18064 |
| 5 | 445859 |
| 6 | 10149621 |
| 7 | 234636215 |
| 8 | 5406312318 |
| 9 | 124597748299 |
| 10 | 2872365166632 |
| 11 | 66225579904258 |
| 12 | 1527174330126193 |
| 13 | 35219108887364016 |
| 14 | 812230463677554629 |
| 15 | 18731997169049673477 |
| 16 | 432004778124039265271 |
[21,56,997,18064,445859,10149621,234636215, 5406312318,124597748299,2872365166632, 66225579904258,1527174330126193,35219108887364016, 812230463677554629,18731997169049673477, 432004778124039265271] |