| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 44 |
| 5 | 163 |
| 6 | 666 |
| 7 | 2985 |
| 8 | 14550 |
| 9 | 76497 |
| 10 | 430746 |
| 11 | 2582447 |
| 12 | 16403028 |
| 13 | 109918745 |
| 14 | 774289168 |
| 15 | 5715471605 |
| 16 | 44087879136 |
| 17 | 354521950931 |
| 18 | 2965359744446 |
| 19 | 25749723493073 |
| 20 | 231719153184018 |
| 21 | 2157494726318233 |
| 22 | 20753996174222510 |
| 23 | 205985762120971167 |
| 24 | 2106795754056142536 |
[1,4,13,44,163,666,2985,14550,76497,430746, 2582447,16403028,109918745,774289168,5715471605, 44087879136,354521950931,2965359744446, 25749723493073,231719153184018,2157494726318233, 20753996174222510,205985762120971167, 2106795754056142536] |