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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 75 |
| 5 | 541 |
| 6 | 4683 |
| 7 | 47292 |
| 8 | 545818 |
| 9 | 7086954 |
| 10 | 102241902 |
| 11 | 1622523210 |
| 12 | 28089336198 |
| 13 | 526810157874 |
| 14 | 10640241569958 |
| 15 | 230256584914356 |
| 16 | 5314976561846952 |
| 17 | 130352566702702344 |
| 18 | 3385021286975255928 |
| 19 | 92786398312428612792 |
| 20 | 2677217312112863784264 |
[1,1,3,13,75,541,4683,47292,545818,7086954, 102241902,1622523210,28089336198,526810157874, 10640241569958,230256584914356,5314976561846952, 130352566702702344,3385021286975255928, 92786398312428612792,2677217312112863784264] |