The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 9 |
| 5 | 25 |
| 6 | 57 |
| 7 | 377 |
| 8 | 5329 |
| 9 | 73458 |
| 10 | 886631 |
| 11 | 17314150 |
| 12 | 625360491 |
| 13 | 29681577990 |
| 14 | 1603029172207 |
| 15 | 115029734984698 |
[1,1,1,9,25,57,377,5329,73458,886631,17314150, 625360491,29681577990,1603029172207, 115029734984698] |