The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 16 |
| 3 | 98 |
| 4 | 544 |
| 5 | 2882 |
| 6 | 14896 |
| 7 | 75938 |
| 8 | 384064 |
| 9 | 1933442 |
| 10 | 9706576 |
| 11 | 48650978 |
| 12 | 243609184 |
| 13 | 1219108802 |
| 14 | 6098732656 |
| 15 | 30503229218 |
| 16 | 152544843904 |
| 17 | 762810312962 |
| 18 | 3814309845136 |
| 19 | 19072324066658 |
| 20 | 95363944856224 |
[0,2,16,98,544,2882,14896,75938,384064,1933442, 9706576,48650978,243609184,1219108802,6098732656, 30503229218,152544843904,762810312962, 3814309845136,19072324066658,95363944856224] |