The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 4 |
| 3 | 6 |
| 4 | 128 |
| 5 | 850 |
| 6 | 13872 |
| 7 | 195314 |
| 8 | 3586592 |
| 9 | 74163618 |
| 10 | 1694735840 |
| 11 | 44196946882 |
| 12 | 1244904944208 |
| 13 | 38788984768274 |
| 14 | 1302631536943856 |
| 15 | 47297768099973330 |
| 16 | 1840951270666885952 |
| 17 | 76501162074673415746 |
| 18 | 3382517582789739956928 |
| 19 | 158445187728836733069986 |
[1,0,4,6,128,850,13872,195314,3586592,74163618, 1694735840,44196946882,1244904944208, 38788984768274,1302631536943856,47297768099973330, 1840951270666885952,76501162074673415746, 3382517582789739956928,158445187728836733069986] |