The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 21 |
| 5 | 55 |
| 6 | 377 |
| 7 | 610 |
| 8 | 17711 |
| 9 | 121393 |
| 10 | 832040 |
| 11 | 5702887 |
| 12 | 19740274219868223167 |
[1,2,8,21,55,377,610,17711,121393,832040,5702887, 19740274219868223167] |