| n | a(n) |
|---|---|
| 4 | 1 |
| 5 | 3 |
| 6 | 12 |
| 7 | 40 |
| 8 | 133 |
| 9 | 427 |
| 10 | 1352 |
| 11 | 4224 |
| 12 | 13080 |
| 13 | 40216 |
| 14 | 122980 |
| 15 | 374452 |
| 16 | 1136226 |
| 17 | 3438150 |
| 18 | 10380048 |
| 19 | 31279728 |
| 20 | 94114125 |
| 21 | 282804759 |
| 22 | 848886180 |
| 23 | 2545759328 |
| 24 | 7628718845 |
| 25 | 22845628531 |
| 26 | 68377674280 |
| 27 | 204560102800 |
| 28 | 611720539235 |
| 29 | 1828673918721 |
[1,3,12,40,133,427,1352,4224,13080,40216,122980, 374452,1136226,3438150,10380048,31279728,94114125, 282804759,848886180,2545759328,7628718845, 22845628531,68377674280,204560102800,611720539235, 1828673918721] |