| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 32 |
| 3 | 165 |
| 4 | 839 |
| 5 | 4237 |
| 6 | 21317 |
| 7 | 107014 |
| 8 | 536500 |
| 9 | 2687362 |
| 10 | 13453606 |
| 11 | 67326816 |
| 12 | 336842092 |
| 13 | 1684953360 |
| 14 | 8427441240 |
| 15 | 42146901045 |
| 16 | 210769862895 |
| 17 | 1053978959265 |
| 18 | 5270372435025 |
| 19 | 26353629438315 |
| 20 | 131774711311995 |
[1,6,32,165,839,4237,21317,107014,536500,2687362, 13453606,67326816,336842092,1684953360,8427441240, 42146901045,210769862895,1053978959265, 5270372435025,26353629438315,131774711311995] |