The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 15 |
| 4 | 49 |
| 5 | 169 |
| 6 | 604 |
| 7 | 2212 |
| 8 | 8244 |
| 9 | 31128 |
| 10 | 118716 |
| 11 | 456337 |
| 12 | 1765251 |
[1,2,5,15,49,169,604,2212,8244,31128,118716, 456337,1765251] |