The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 5 |
| 3 | 20 |
| 4 | 179 |
| 5 | 3353 |
| 6 | 108281 |
| 7 | 6601649 |
| 8 | 818828659 |
| 9 | 196362508518 |
| 10 | 91040908551719 |
[1,5,20,179,3353,108281,6601649,818828659, 196362508518,91040908551719] |