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| n | a(n) |
|---|---|
| 4 | 0 |
| 5 | 42 |
| 6 | 274 |
| 7 | 1227 |
| 8 | 4833 |
| 9 | 18827 |
| 10 | 75693 |
| 11 | 304900 |
| 12 | 1212960 |
| 13 | 4753020 |
| 14 | 18410363 |
| 15 | 70943107 |
| 16 | 272701262 |
| 17 | 1046410914 |
| 18 | 4007815161 |
| 19 | 15319362279 |
| 20 | 58456445860 |
| 21 | 222775782355 |
| 22 | 848216866767 |
| 23 | 3227396592600 |
| 24 | 12273205919568 |
| 25 | 46650941505906 |
| 26 | 177252609519698 |
| 27 | 673266690295879 |
[0,42,274,1227,4833,18827,75693,304900,1212960, 4753020,18410363,70943107,272701262,1046410914, 4007815161,15319362279,58456445860,222775782355, 848216866767,3227396592600,12273205919568, 46650941505906,177252609519698,673266690295879] |