| n | a(n) |
|---|---|
| 0 | -1 |
| 1 | 1 |
| 2 | 8 |
| 3 | 34 |
| 4 | 131 |
| 5 | 493 |
| 6 | 1844 |
| 7 | 6886 |
| 8 | 25703 |
| 9 | 95929 |
| 10 | 358016 |
| 11 | 1336138 |
| 12 | 4986539 |
| 13 | 18610021 |
| 14 | 69453548 |
| 15 | 259204174 |
| 16 | 967363151 |
| 17 | 3610248433 |
| 18 | 13473630584 |
| 19 | 50284273906 |
| 20 | 187663465043 |
| 21 | 700369586269 |
| 22 | 2613814880036 |
| 23 | 9754889933878 |
| 24 | 36405744855479 |
| 25 | 135868089488041 |
[-1,1,8,34,131,493,1844,6886,25703,95929,358016, 1336138,4986539,18610021,69453548,259204174, 967363151,3610248433,13473630584,50284273906, 187663465043,700369586269,2613814880036, 9754889933878,36405744855479,135868089488041] |