| n | a(n) |
|---|---|
| 6 | 1 |
| 7 | 7 |
| 8 | 19 |
| 9 | 37 |
| 10 | 61 |
| 11 | 215 |
| 12 | 976 |
| 13 | 6510 |
| 14 | 31895 |
| 15 | 148311 |
| 16 | 835105 |
| 17 | 6965183 |
| 18 | 70259384 |
| 19 | 771053702 |
| 20 | 8287139754 |
| 21 | 101882179551 |
[1,7,19,37,61,215,976,6510,31895,148311,835105, 6965183,70259384,771053702,8287139754, 101882179551] |