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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 5 |
| 3 | 31 |
| 4 | 205 |
| 5 | 1376 |
| 6 | 9251 |
| 7 | 62210 |
| 8 | 418361 |
| 9 | 2813485 |
| 10 | 18920751 |
| 11 | 127242501 |
| 12 | 855708865 |
| 13 | 5754662616 |
| 14 | 38700243965 |
| 15 | 260260067876 |
| 16 | 1750255192001 |
| 17 | 11770508100345 |
| 18 | 79156948982921 |
| 19 | 532332378421395 |
| 20 | 3579947998967501 |
| 21 | 24075236064574376 |
[1,5,31,205,1376,9251,62210,418361,2813485, 18920751,127242501,855708865,5754662616, 38700243965,260260067876,1750255192001, 11770508100345,79156948982921,532332378421395, 3579947998967501,24075236064574376] |