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| n | a(n) |
|---|---|
| 1 | 8 |
| 2 | 64 |
| 3 | 216 |
| 4 | 940 |
| 5 | 3776 |
| 6 | 15652 |
| 7 | 64176 |
| 8 | 263976 |
| 9 | 1084380 |
| 10 | 4456764 |
| 11 | 18314496 |
| 12 | 75265524 |
| 13 | 309304372 |
| 14 | 1271098480 |
| 15 | 5223614592 |
| 16 | 21466618480 |
| 17 | 88217749664 |
| 18 | 362533690524 |
| 19 | 1489843800060 |
| 20 | 6122560903368 |
| 21 | 25160860321572 |
| 22 | 103399362536912 |
[8,64,216,940,3776,15652,64176,263976,1084380, 4456764,18314496,75265524,309304372,1271098480, 5223614592,21466618480,88217749664,362533690524, 1489843800060,6122560903368,25160860321572, 103399362536912] |