| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 10 |
| 5 | 25 |
| 6 | 68 |
| 7 | 186 |
| 8 | 522 |
| 9 | 1479 |
| 10 | 4246 |
| 11 | 12289 |
| 12 | 35872 |
| 13 | 105411 |
| 14 | 311662 |
| 15 | 926270 |
| 16 | 2765778 |
| 17 | 8292296 |
| 18 | 24953437 |
| 19 | 75338686 |
| 20 | 228140842 |
| 21 | 692733127 |
| 22 | 2108652750 |
| 23 | 6433255041 |
| 24 | 19668210742 |
| 25 | 60247367313 |
| 26 | 184879648441 |
| 27 | 568281131800 |
[1,1,2,4,10,25,68,186,522,1479,4246,12289,35872, 105411,311662,926270,2765778,8292296,24953437, 75338686,228140842,692733127,2108652750, 6433255041,19668210742,60247367313,184879648441, 568281131800] |