| n | a(n) |
|---|---|
| 1 | 28 |
| 2 | 784 |
| 3 | 11990 |
| 4 | 116692 |
| 5 | 816361 |
| 6 | 4480391 |
| 7 | 20568693 |
| 8 | 82733667 |
| 9 | 301228048 |
| 10 | 1015242774 |
| 11 | 3216158234 |
| 12 | 9677475342 |
| 13 | 27865037554 |
| 14 | 77192516888 |
| 15 | 206580752375 |
| 16 | 535811566173 |
| 17 | 1350500930653 |
| 18 | 3315175437671 |
| 19 | 7940967421582 |
| 20 | 18591190564502 |
[28,784,11990,116692,816361,4480391,20568693, 82733667,301228048,1015242774,3216158234, 9677475342,27865037554,77192516888,206580752375, 535811566173,1350500930653,3315175437671, 7940967421582,18591190564502] |