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| n | a(n) |
|---|---|
| 1 | 8 |
| 2 | 64 |
| 3 | 216 |
| 4 | 984 |
| 5 | 3984 |
| 6 | 16872 |
| 7 | 70216 |
| 8 | 294192 |
| 9 | 1229400 |
| 10 | 5142728 |
| 11 | 21504256 |
| 12 | 89933368 |
| 13 | 376090120 |
| 14 | 1572797488 |
| 15 | 6577333928 |
| 16 | 27506063752 |
| 17 | 115028758000 |
| 18 | 481043815944 |
| 19 | 2011697870456 |
| 20 | 8412806681456 |
| 21 | 35181880551080 |
| 22 | 147128631386264 |
[8,64,216,984,3984,16872,70216,294192,1229400, 5142728,21504256,89933368,376090120,1572797488, 6577333928,27506063752,115028758000,481043815944, 2011697870456,8412806681456,35181880551080, 147128631386264] |