| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 11 |
| 5 | 31 |
| 6 | 106 |
| 7 | 372 |
| 8 | 1500 |
| 9 | 6220 |
| 10 | 28696 |
| 11 | 136016 |
| 12 | 702802 |
| 13 | 3727946 |
| 14 | 21253324 |
| 15 | 124231096 |
| 16 | 772458366 |
| 17 | 4918962462 |
| 18 | 33061094812 |
| 19 | 227303566648 |
| 20 | 1639389311906 |
| 21 | 12082068225466 |
| 22 | 92951836390172 |
| 23 | 729991698024568 |
| 24 | 5960615982017512 |
| 25 | 49636995406898376 |
[1,1,2,4,11,31,106,372,1500,6220,28696,136016, 702802,3727946,21253324,124231096,772458366, 4918962462,33061094812,227303566648,1639389311906, 12082068225466,92951836390172,729991698024568, 5960615982017512,49636995406898376] |