| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 9 |
| 6 | 20 |
| 7 | 51 |
| 8 | 128 |
| 9 | 345 |
| 10 | 940 |
| 11 | 2632 |
| 12 | 7450 |
| 13 | 21434 |
| 14 | 62174 |
| 15 | 182146 |
| 16 | 537369 |
| 17 | 1596133 |
| 18 | 4767379 |
| 19 | 14312919 |
| 20 | 43162856 |
| 21 | 130695821 |
| 22 | 397184252 |
| 23 | 1211057426 |
| 24 | 3703794849 |
| 25 | 11358759346 |
| 26 | 34923477315 |
| 27 | 107627138308 |
| 28 | 332404636811 |
[1,1,2,4,9,20,51,128,345,940,2632,7450,21434, 62174,182146,537369,1596133,4767379,14312919, 43162856,130695821,397184252,1211057426, 3703794849,11358759346,34923477315,107627138308, 332404636811] |