| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 17 |
| 5 | 78 |
| 6 | 449 |
| 7 | 3060 |
| 8 | 23920 |
| 9 | 210930 |
| 10 | 2070941 |
| 11 | 22403815 |
| 12 | 264772350 |
| 13 | 3393900116 |
| 14 | 46897528867 |
| 15 | 694936109572 |
| 16 | 10992625733215 |
| 17 | 184875978240421 |
| 18 | 3294153794102035 |
| 19 | 61989985034465560 |
| 20 | 1228528794319408361 |
| 21 | 25575735809013137690 |
| 22 | 558016054014832095049 |
[1,1,2,5,17,78,449,3060,23920,210930,2070941, 22403815,264772350,3393900116,46897528867, 694936109572,10992625733215,184875978240421, 3294153794102035,61989985034465560, 1228528794319408361,25575735809013137690, 558016054014832095049] |