| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 8 |
| 3 | 56 |
| 4 | 385 |
| 5 | 2640 |
| 6 | 18096 |
| 7 | 124033 |
| 8 | 850136 |
| 9 | 5826920 |
| 10 | 39938305 |
| 11 | 273741216 |
| 12 | 1876250208 |
| 13 | 12860010241 |
| 14 | 88143821480 |
| 15 | 604146740120 |
| 16 | 4140883359361 |
| 17 | 28382036775408 |
| 18 | 194533374068496 |
| 19 | 1333351581704065 |
| 20 | 9138927697859960 |
[1,8,56,385,2640,18096,124033,850136,5826920, 39938305,273741216,1876250208,12860010241, 88143821480,604146740120,4140883359361, 28382036775408,194533374068496,1333351581704065, 9138927697859960] |