| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 7 |
| 2 | 37 |
| 3 | 175 |
| 4 | 792 |
| 5 | 3521 |
| 6 | 15539 |
| 7 | 68369 |
| 8 | 300431 |
| 9 | 1319472 |
| 10 | 5793745 |
| 11 | 25437727 |
| 12 | 111681277 |
| 13 | 490315231 |
| 14 | 2152620360 |
| 15 | 9450575729 |
| 16 | 41490490763 |
| 17 | 182153978153 |
| 18 | 799702876895 |
| 19 | 3510901281888 |
| 20 | 15413758929889 |
| 21 | 67670362004791 |
| 22 | 297090274041301 |
| 23 | 1304302623454159 |
| 24 | 5726223576745848 |
[1,7,37,175,792,3521,15539,68369,300431,1319472, 5793745,25437727,111681277,490315231,2152620360, 9450575729,41490490763,182153978153,799702876895, 3510901281888,15413758929889,67670362004791, 297090274041301,1304302623454159,5726223576745848] |