The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 28 |
| 3 | 152 |
| 4 | 6928 |
| 5 | 2225408 |
| 6 | 348750400 |
| 7 | 38567316608 |
| 8 | 5024551512320 |
| 9 | 2238520490011648 |
| 10 | 1265695140964379648 |
| 11 | 555587429710072952832 |
| 12 | 218348017328527789264896 |
| 13 | 124784882666107086189330432 |
[1,4,28,152,6928,2225408,348750400,38567316608, 5024551512320,2238520490011648, 1265695140964379648,555587429710072952832, 218348017328527789264896, 124784882666107086189330432] |