| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 20 |
| 3 | 162 |
| 4 | 1442 |
| 5 | 12688 |
| 6 | 110720 |
| 7 | 970828 |
| 8 | 8489090 |
| 9 | 74301713 |
| 10 | 650080567 |
| 11 | 5688284025 |
| 12 | 49771429169 |
| 13 | 435493321644 |
| 14 | 3810502524152 |
| 15 | 33341324878142 |
| 16 | 291731631862014 |
| 17 | 2552608002906241 |
| 18 | 22334937934827800 |
| 19 | 195427359369424289 |
[1,20,162,1442,12688,110720,970828,8489090, 74301713,650080567,5688284025,49771429169, 435493321644,3810502524152,33341324878142, 291731631862014,2552608002906241, 22334937934827800,195427359369424289] |