| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 6 |
| 5 | 28 |
| 6 | 122 |
| 7 | 516 |
| 8 | 2142 |
| 9 | 8776 |
| 10 | 35630 |
| 11 | 143757 |
| 12 | 577548 |
| 13 | 2313400 |
| 14 | 9246556 |
| 15 | 36899291 |
| 16 | 147073062 |
| 17 | 585662952 |
| 18 | 2330527172 |
| 19 | 9268803248 |
| 20 | 36847836764 |
| 21 | 146441131058 |
| 22 | 581850689938 |
| 23 | 2311451765318 |
| 24 | 9181309423676 |
| 25 | 36466002547328 |
| 26 | 144826879361752 |
| 27 | 575173217031049 |
[0,0,0,1,6,28,122,516,2142,8776,35630,143757, 577548,2313400,9246556,36899291,147073062, 585662952,2330527172,9268803248,36847836764, 146441131058,581850689938,2311451765318, 9181309423676,36466002547328,144826879361752, 575173217031049] |