| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 55 |
| 6 | 232 |
| 7 | 1161 |
| 8 | 6643 |
| 9 | 44566 |
| 10 | 327064 |
| 11 | 2709050 |
| 12 | 24312028 |
| 13 | 240833770 |
| 14 | 2546215687 |
| 15 | 29251369570 |
| 16 | 355838858402 |
| 17 | 4658866773664 |
| 18 | 64127566159756 |
| 19 | 940320691236206 |
[1,1,2,5,15,55,232,1161,6643,44566,327064,2709050, 24312028,240833770,2546215687,29251369570, 355838858402,4658866773664,64127566159756, 940320691236206] |
