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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 21 |
| 3 | 85 |
| 4 | 781 |
| 5 | 4673 |
| 6 | 34981 |
| 7 | 233265 |
| 8 | 1653229 |
| 9 | 11354857 |
| 10 | 79290645 |
| 11 | 548972737 |
| 12 | 3817993565 |
| 13 | 26491584361 |
| 14 | 184040357765 |
| 15 | 1277739038129 |
| 16 | 8873937621293 |
| 17 | 61619077914745 |
| 18 | 427911161639829 |
| 19 | 2971470559369153 |
| 20 | 20634790487757629 |
[1,21,85,781,4673,34981,233265,1653229,11354857, 79290645,548972737,3817993565,26491584361, 184040357765,1277739038129,8873937621293, 61619077914745,427911161639829,2971470559369153, 20634790487757629] |