| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 36 |
| 3 | 352 |
| 4 | 3620 |
| 5 | 38304 |
| 6 | 412895 |
| 7 | 4509152 |
| 8 | 49721364 |
| 9 | 552359680 |
| 10 | 6172578126 |
| 11 | 69310337760 |
| 12 | 781375805392 |
| 13 | 8838533555180 |
| 14 | 100264250360835 |
| 15 | 1140219161743552 |
| 16 | 12994808897190788 |
| 17 | 148381034370726096 |
[1,4,36,352,3620,38304,412895,4509152,49721364, 552359680,6172578126,69310337760,781375805392, 8838533555180,100264250360835,1140219161743552, 12994808897190788,148381034370726096] |