The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 8 |
| 3 | 52 |
| 4 | 340 |
| 5 | 2120 |
| 6 | 12966 |
| 7 | 78404 |
| 8 | 471049 |
| 9 | 2819296 |
| 10 | 16836187 |
| 11 | 100413044 |
| 12 | 598466970 |
| 13 | 3565829520 |
| 14 | 21245133183 |
| 15 | 126592343380 |
| 16 | 754484832586 |
| 17 | 4497987650048 |
| 18 | 26824346741653 |
| 19 | 160027308774544 |
| 20 | 955033911144732 |
| 21 | 5701712685169392 |
| 22 | 34052840254416123 |
| 23 | 203451441144122916 |
[1,2,8,52,340,2120,12966,78404,471049,2819296, 16836187,100413044,598466970,3565829520, 21245133183,126592343380,754484832586, 4497987650048,26824346741653,160027308774544, 955033911144732,5701712685169392, 34052840254416123,203451441144122916] |