The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 48 |
| 5 | 160 |
| 6 | 722 |
| 7 | 2639 |
| 8 | 12302 |
| 9 | 47370 |
| 10 | 223638 |
| 11 | 891897 |
| 12 | 4264396 |
| 13 | 17419445 |
| 14 | 83826126 |
| 15 | 348887426 |
| 16 | 1688966347 |
| 17 | 7129241116 |
| 18 | 34645839644 |
| 19 | 147958621019 |
| 20 | 721420188206 |
| 21 | 3109847454343 |
| 22 | 15201470731470 |
| 23 | 66054784486884 |
| 24 | 323562953643088 |
| 25 | 1415428375412890 |
| 26 | 6945538586626436 |
| 27 | 30561041741638814 |
[1,1,4,11,48,160,722,2639,12302,47370,223638, 891897,4264396,17419445,83826126,348887426, 1688966347,7129241116,34645839644,147958621019, 721420188206,3109847454343,15201470731470, 66054784486884,323562953643088,1415428375412890, 6945538586626436,30561041741638814] |