The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 6 |
| 5 | 34 |
| 6 | 179 |
| 7 | 915 |
| 8 | 4607 |
| 9 | 22988 |
| 10 | 114090 |
| 11 | 564359 |
| 12 | 2785921 |
| 13 | 13735074 |
| 14 | 67665208 |
| 15 | 333211828 |
| 16 | 1640575047 |
| 17 | 8077199130 |
| 18 | 39770520844 |
| 19 | 195852723348 |
| 20 | 964689515033 |
| 21 | 4752800817185 |
| 22 | 23422061819883 |
| 23 | 115456855588378 |
| 24 | 569293729146929 |
| 25 | 2807864888917275 |
[0,0,0,1,6,34,179,915,4607,22988,114090,564359, 2785921,13735074,67665208,333211828,1640575047, 8077199130,39770520844,195852723348,964689515033, 4752800817185,23422061819883,115456855588378, 569293729146929,2807864888917275] |