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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 7 |
| 2 | 43 |
| 3 | 255 |
| 4 | 1491 |
| 5 | 8659 |
| 6 | 50107 |
| 7 | 289375 |
| 8 | 1669291 |
| 9 | 9623427 |
| 10 | 55460835 |
| 11 | 319583823 |
| 12 | 1841526051 |
| 13 | 10612066227 |
| 14 | 61160827083 |
| 15 | 352543298751 |
| 16 | 2032480521819 |
| 17 | 11719811413027 |
| 18 | 67592446165363 |
| 19 | 389906344880815 |
| 20 | 2249609496664531 |
[1,7,43,255,1491,8659,50107,289375,1669291, 9623427,55460835,319583823,1841526051,10612066227, 61160827083,352543298751,2032480521819, 11719811413027,67592446165363,389906344880815, 2249609496664531] |