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| n | a(n) |
|---|---|
| 20 | 1 |
| 21 | 21 |
| 22 | 279 |
| 23 | 2914 |
| 24 | 25771 |
| 25 | 201454 |
| 26 | 1433041 |
| 27 | 9469739 |
| 28 | 59016909 |
| 29 | 350829247 |
| 30 | 2006522229 |
| 31 | 11114963598 |
| 32 | 59942608977 |
| 33 | 316006164419 |
| 34 | 1633786190804 |
| 35 | 8305527032158 |
| 36 | 41603804525306 |
| 37 | 205707814621939 |
| 38 | 1005426524364506 |
| 39 | 4863626362504773 |
| 40 | 23309223454202475 |
| 41 | 110773290856066906 |
[1,21,279,2914,25771,201454,1433041,9469739, 59016909,350829247,2006522229,11114963598, 59942608977,316006164419,1633786190804, 8305527032158,41603804525306,205707814621939, 1005426524364506,4863626362504773, 23309223454202475,110773290856066906] |