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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 8 |
| 2 | 48 |
| 3 | 304 |
| 4 | 1904 |
| 5 | 11952 |
| 6 | 74992 |
| 7 | 470576 |
| 8 | 2952816 |
| 9 | 18528688 |
| 10 | 116265968 |
| 11 | 729559344 |
| 12 | 4577924464 |
| 13 | 28726097072 |
| 14 | 180253881072 |
| 15 | 1131078181936 |
| 16 | 7097421958256 |
| 17 | 44535735246768 |
| 18 | 279458051899888 |
| 19 | 1753576141473584 |
[1,8,48,304,1904,11952,74992,470576,2952816, 18528688,116265968,729559344,4577924464, 28726097072,180253881072,1131078181936, 7097421958256,44535735246768,279458051899888, 1753576141473584] |