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| n | a(n) |
|---|---|
| 1 | 1640 |
| 2 | 6908 |
| 3 | 34608 |
| 4 | 206556 |
| 5 | 1303920 |
| 6 | 8616068 |
| 7 | 58209538 |
| 8 | 400984904 |
| 9 | 2799816642 |
| 10 | 19780619488 |
| 11 | 141031726484 |
| 12 | 1013269795948 |
| 13 | 7324436942360 |
| 14 | 53208482346514 |
| 15 | 388059888524356 |
| 16 | 2839169810686872 |
| 17 | 20824365934488100 |
| 18 | 153044591416091762 |
[1640,6908,34608,206556,1303920,8616068,58209538, 400984904,2799816642,19780619488,141031726484, 1013269795948,7324436942360,53208482346514, 388059888524356,2839169810686872, 20824365934488100,153044591416091762] |