The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 6 |
| 3 | 12 |
| 4 | 28 |
| 5 | 88 |
| 6 | 444 |
| 7 | 3671 |
| 8 | 47981 |
| 9 | 976631 |
| 10 | 29554002 |
| 11 | 1326494644 |
[1,3,6,12,28,88,444,3671,47981,976631,29554002, 1326494644] |