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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 9 |
| 2 | 73 |
| 3 | 577 |
| 4 | 4529 |
| 5 | 35481 |
| 6 | 277817 |
| 7 | 2174993 |
| 8 | 17027041 |
| 9 | 133295529 |
| 10 | 1043495593 |
| 11 | 8168931937 |
| 12 | 63949894289 |
| 13 | 500627099961 |
| 14 | 3919122796697 |
| 15 | 30680567267633 |
| 16 | 240180585132481 |
| 17 | 1880236207775049 |
| 18 | 14719292130498313 |
| 19 | 115228905772807297 |
| 20 | 902061091509601649 |
[1,9,73,577,4529,35481,277817,2174993,17027041, 133295529,1043495593,8168931937,63949894289, 500627099961,3919122796697,30680567267633, 240180585132481,1880236207775049, 14719292130498313,115228905772807297, 902061091509601649] |