| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 12 |
| 5 | 34 |
| 6 | 96 |
| 7 | 272 |
| 8 | 772 |
| 9 | 2192 |
| 10 | 6224 |
| 11 | 17672 |
| 12 | 50176 |
| 13 | 142464 |
| 14 | 404496 |
| 15 | 1148480 |
| 16 | 3260864 |
| 17 | 9258528 |
| 18 | 26287616 |
| 19 | 74638080 |
| 20 | 211918912 |
| 21 | 601698560 |
| 22 | 1708394752 |
| 23 | 4850622592 |
| 24 | 13772308480 |
| 25 | 39103533056 |
| 26 | 111026143488 |
| 27 | 315235058688 |
| 28 | 895042726912 |
| 29 | 2541282959872 |
[0,0,1,4,12,34,96,272,772,2192,6224,17672,50176, 142464,404496,1148480,3260864,9258528,26287616, 74638080,211918912,601698560,1708394752, 4850622592,13772308480,39103533056,111026143488, 315235058688,895042726912,2541282959872] |