The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 3 |
| 6 | 11 |
| 7 | 31 |
| 8 | 107 |
| 9 | 597 |
| 10 | 4235 |
| 11 | 35993 |
| 12 | 378513 |
| 13 | 5151733 |
| 14 | 87563339 |
| 15 | 1913743005 |
| 16 | 52850470565 |
| 17 | 1858867426265 |
| 18 | 81756583423405 |
| 19 | 4581414733191763 |
| 20 | 324047679491641949 |
| 21 | 29188263592896961077 |
[1,1,1,1,3,11,31,107,597,4235,35993,378513, 5151733,87563339,1913743005,52850470565, 1858867426265,81756583423405,4581414733191763, 324047679491641949,29188263592896961077] |