| n | a(n) |
|---|---|
| 1 | 7 |
| 2 | 47 |
| 3 | 342 |
| 4 | 2754 |
| 5 | 24552 |
| 6 | 241128 |
| 7 | 2592720 |
| 8 | 30334320 |
| 9 | 383970240 |
| 10 | 5231113920 |
| 11 | 76349105280 |
| 12 | 1188825724800 |
| 13 | 19675048780800 |
[7,47,342,2754,24552,241128,2592720,30334320, 383970240,5231113920,76349105280,1188825724800, 19675048780800] |