The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 48 |
| 6 | 182 |
| 7 | 868 |
| 8 | 5752 |
| 9 | 22952 |
| 10 | 131766 |
| 11 | 912964 |
| 12 | 7556978 |
| 13 | 52602390 |
| 14 | 432795244 |
| 15 | 4121203656 |
| 16 | 44335718598 |
| 17 | 416447624724 |
[1,2,6,24,48,182,868,5752,22952,131766,912964, 7556978,52602390,432795244,4121203656,44335718598, 416447624724] |