The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 65 |
| 6 | 1242 |
| 7 | 55546 |
| 8 | 5603265 |
| 9 | 1280956817 |
| 10 | 661075536443 |
| 11 | 771059112373171 |
| 12 | 2031433178217758354 |
[1,1,2,7,65,1242,55546,5603265,1280956817, 661075536443,771059112373171,2031433178217758354] |