The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 60 |
| 4 | 587 |
| 5 | 7277 |
| 6 | 91470 |
| 7 | 1151734 |
| 8 | 14116900 |
| 9 | 166220264 |
| 10 | 1888964884 |
| 11 | 20910204634 |
[1,6,60,587,7277,91470,1151734,14116900,166220264, 1888964884,20910204634] |