The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 14 |
| 5 | 41 |
| 6 | 127 |
| 7 | 400 |
| 8 | 1297 |
| 9 | 4520 |
| 10 | 17064 |
| 11 | 64857 |
| 12 | 262286 |
| 13 | 1156325 |
| 14 | 5199261 |
| 15 | 23835336 |
| 16 | 117674608 |
| 17 | 609741279 |
| 18 | 3268286263 |
| 19 | 18109939168 |
| 20 | 102866828839 |
| 21 | 620474818814 |
| 22 | 4005211833858 |
| 23 | 25747541532731 |
| 24 | 166978138395205 |
| 25 | 1168773990780772 |
[0,1,4,14,41,127,400,1297,4520,17064,64857,262286, 1156325,5199261,23835336,117674608,609741279, 3268286263,18109939168,102866828839,620474818814, 4005211833858,25747541532731,166978138395205, 1168773990780772] |