| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 4 |
| 3 | 0 |
| 4 | 20 |
| 5 | 0 |
| 6 | 84 |
| 7 | 16 |
| 8 | 292 |
| 9 | 64 |
| 10 | 1172 |
| 11 | 272 |
| 12 | 4644 |
| 13 | 1344 |
| 14 | 19092 |
| 15 | 5392 |
| 16 | 76324 |
| 17 | 21824 |
| 18 | 305300 |
| 19 | 87312 |
| 20 | 1221156 |
| 21 | 349504 |
| 22 | 4885140 |
| 23 | 1398032 |
| 24 | 19540516 |
| 25 | 5592384 |
| 26 | 78162068 |
| 27 | 22369552 |
| 28 | 312648228 |
| 29 | 89478464 |
| 30 | 1250593428 |
| 31 | 357913872 |
| 32 | 5002373668 |
| 33 | 1431655744 |
| 34 | 20009494676 |
[1,0,4,0,20,0,84,16,292,64,1172,272,4644,1344, 19092,5392,76324,21824,305300,87312,1221156, 349504,4885140,1398032,19540516,5592384,78162068, 22369552,312648228,89478464,1250593428,357913872, 5002373668,1431655744,20009494676] |