The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 8 |
| 4 | 64 |
| 5 | 824 |
| 6 | 12968 |
| 7 | 252720 |
| 8 | 5789712 |
| 9 | 153169440 |
| 10 | 4589004192 |
| 11 | 153643615872 |
| 12 | 5684390364288 |
| 13 | 230307823878144 |
| 14 | 10141452865049088 |
| 15 | 482259966649655808 |
| 16 | 24630247225278881280 |
| 17 | 1344614199041549399040 |
| 18 | 78137673004382654223360 |
[1,1,8,64,824,12968,252720,5789712,153169440, 4589004192,153643615872,5684390364288, 230307823878144,10141452865049088, 482259966649655808,24630247225278881280, 1344614199041549399040,78137673004382654223360] |