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| n | a(n) |
|---|---|
| 1 | 512 |
| 2 | 2700 |
| 3 | 12680 |
| 4 | 47816 |
| 5 | 178752 |
| 6 | 618856 |
| 7 | 2201616 |
| 8 | 7686444 |
| 9 | 27456624 |
| 10 | 97621664 |
| 11 | 351178392 |
| 12 | 1260927472 |
| 13 | 4551240904 |
| 14 | 16412577588 |
| 15 | 59322609368 |
| 16 | 214326499116 |
| 17 | 775118000256 |
| 18 | 2802669569216 |
| 19 | 10138358665920 |
| 20 | 36671008548568 |
[512,2700,12680,47816,178752,618856,2201616, 7686444,27456624,97621664,351178392,1260927472, 4551240904,16412577588,59322609368,214326499116, 775118000256,2802669569216,10138358665920, 36671008548568] |