| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 14 |
| 5 | 42 |
| 6 | 131 |
| 7 | 427 |
| 8 | 1413 |
| 9 | 4784 |
| 10 | 16416 |
| 11 | 57042 |
| 12 | 200151 |
| 13 | 708109 |
| 14 | 2522559 |
| 15 | 9039042 |
| 16 | 32550884 |
| 17 | 117725760 |
| 18 | 427372532 |
| 19 | 1556523664 |
| 20 | 5685148711 |
| 21 | 20816785068 |
| 22 | 76390832952 |
| 23 | 280874946775 |
| 24 | 1034505345468 |
| 25 | 3816077176898 |
| 26 | 14095932284899 |
| 27 | 52131389039054 |
[1,1,2,5,14,42,131,427,1413,4784,16416,57042, 200151,708109,2522559,9039042,32550884,117725760, 427372532,1556523664,5685148711,20816785068, 76390832952,280874946775,1034505345468, 3816077176898,14095932284899,52131389039054] |