The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 8 |
| 2 | 44 |
| 3 | 192 |
| 4 | 726 |
| 5 | 2464 |
| 6 | 7704 |
| 7 | 22528 |
| 8 | 62337 |
| 9 | 164560 |
| 10 | 417140 |
| 11 | 1020416 |
| 12 | 2418710 |
| 13 | 5573568 |
| 14 | 12520744 |
| 15 | 27484160 |
| 16 | 59068372 |
| 17 | 124505880 |
| 18 | 257770964 |
| 19 | 524871424 |
| 20 | 1052316364 |
| 21 | 2079491744 |
| 22 | 4053978040 |
| 23 | 7803219968 |
| 24 | 14840711765 |
| 25 | 27907041392 |
| 26 | 51917588800 |
| 27 | 95608651776 |
[1,8,44,192,726,2464,7704,22528,62337,164560, 417140,1020416,2418710,5573568,12520744,27484160, 59068372,124505880,257770964,524871424,1052316364, 2079491744,4053978040,7803219968,14840711765, 27907041392,51917588800,95608651776] |