| n | a(n) |
|---|---|
| 0 | 3 |
| 1 | 13 |
| 2 | 56 |
| 3 | 241 |
| 4 | 1037 |
| 5 | 4462 |
| 6 | 19199 |
| 7 | 82609 |
| 8 | 355448 |
| 9 | 1529413 |
| 10 | 6580721 |
| 11 | 28315366 |
| 12 | 121834667 |
| 13 | 524227237 |
| 14 | 2255632184 |
| 15 | 9705479209 |
| 16 | 41760499493 |
| 17 | 179686059838 |
| 18 | 773148800711 |
| 19 | 3326685824041 |
| 20 | 14313982718072 |
[3,13,56,241,1037,4462,19199,82609,355448,1529413, 6580721,28315366,121834667,524227237,2255632184, 9705479209,41760499493,179686059838,773148800711, 3326685824041,14313982718072] |