The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 12 |
| 3 | 222 |
| 4 | 8120 |
| 5 | 478810 |
| 6 | 41517828 |
| 7 | 4965965942 |
| 8 | 783389808112 |
| 9 | 157572900435762 |
| 10 | 39359784790117500 |
| 11 | 11953192658425797262 |
| 12 | 4337232551752795660968 |
| 13 | 1853172813592086586350218 |
[0,2,12,222,8120,478810,41517828,4965965942, 783389808112,157572900435762,39359784790117500, 11953192658425797262,4337232551752795660968, 1853172813592086586350218] |