| n | a(n) |
|---|---|
| 1 | 8 |
| 2 | 64 |
| 3 | 400 |
| 4 | 2500 |
| 5 | 15200 |
| 6 | 92416 |
| 7 | 560576 |
| 8 | 3400336 |
| 9 | 20623296 |
| 10 | 125081856 |
| 11 | 758633088 |
| 12 | 4601180224 |
| 13 | 27906627456 |
| 14 | 169256542464 |
| 15 | 1026558406656 |
| 16 | 6226182733824 |
| 17 | 37762441850880 |
| 18 | 229033113145600 |
| 19 | 1389109506607360 |
| 20 | 8425092751196416 |
[8,64,400,2500,15200,92416,560576,3400336, 20623296,125081856,758633088,4601180224, 27906627456,169256542464,1026558406656, 6226182733824,37762441850880,229033113145600, 1389109506607360,8425092751196416] |