| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 20 |
| 3 | 76 |
| 4 | 292 |
| 5 | 1132 |
| 6 | 4420 |
| 7 | 17356 |
| 8 | 68452 |
| 9 | 270892 |
| 10 | 1074820 |
| 11 | 4273036 |
| 12 | 17013412 |
| 13 | 67817452 |
| 14 | 270561220 |
| 15 | 1080119116 |
[1,5,20,76,292,1132,4420,17356,68452,270892, 1074820,4273036,17013412,67817452,270561220, 1080119116] |