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| n | a(n) |
|---|---|
| 1 | 20 |
| 2 | 400 |
| 3 | 3354 |
| 4 | 24711 |
| 5 | 181626 |
| 6 | 1288734 |
| 7 | 8951764 |
| 8 | 61078115 |
| 9 | 412004463 |
| 10 | 2754584607 |
| 11 | 18305734529 |
| 12 | 121093197502 |
| 13 | 798454543443 |
| 14 | 5251973517844 |
| 15 | 34485457416930 |
| 16 | 226141081539515 |
| 17 | 1481522016356561 |
| 18 | 9698977844261838 |
| 19 | 63462246846069728 |
[20,400,3354,24711,181626,1288734,8951764, 61078115,412004463,2754584607,18305734529, 121093197502,798454543443,5251973517844, 34485457416930,226141081539515,1481522016356561, 9698977844261838,63462246846069728] |