The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 4 |
| 3 | 14 |
| 4 | 36 |
| 5 | 116 |
| 6 | 378 |
| 7 | 1178 |
| 8 | 3700 |
| 9 | 11694 |
| 10 | 36852 |
| 11 | 116082 |
| 12 | 365886 |
| 13 | 1153178 |
| 14 | 3634154 |
| 15 | 11453184 |
| 16 | 36095524 |
| 17 | 113756584 |
| 18 | 358508862 |
| 19 | 1129858168 |
| 20 | 3560801564 |
| 21 | 11222032838 |
| 22 | 35366766278 |
| 23 | 111460034016 |
| 24 | 351271552234 |
| 25 | 1107048863804 |
| 26 | 3488916716866 |
| 27 | 10995485596894 |
[0,0,4,14,36,116,378,1178,3700,11694,36852,116082, 365886,1153178,3634154,11453184,36095524, 113756584,358508862,1129858168,3560801564, 11222032838,35366766278,111460034016,351271552234, 1107048863804,3488916716866,10995485596894] |