| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 21 |
| 6 | 110 |
| 7 | 853 |
| 8 | 11111 |
| 9 | 261077 |
| 10 | 11716550 |
| 11 | 1006700565 |
| 12 | 164059830354 |
| 13 | 50335907869219 |
| 14 | 29003487462847208 |
| 15 | 31397381142761241918 |
| 16 | 63969560113225176165145 |
| 17 | 245871831682084026519528568 |
[0,1,2,5,21,110,853,11111,261077,11716550, 1006700565,164059830354,50335907869219, 29003487462847208,31397381142761241918, 63969560113225176165145, 245871831682084026519528568] |