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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 4 |
| 5 | 31 |
| 6 | 146 |
| 7 | 1289 |
| 8 | 7736 |
| 9 | 85831 |
| 10 | 641302 |
| 11 | 8732989 |
| 12 | 78432212 |
| 13 | 1270475155 |
| 14 | 13338831858 |
| 15 | 250740220345 |
| 16 | 3013809363056 |
| 17 | 64512904742895 |
| 18 | 873589792390382 |
| 19 | 20982459271174517 |
| 20 | 316070362138732172 |
| 21 | 8418423492219771211 |
| 22 | 139628838506569935338 |
| 23 | 4084524856346911809777 |
[0,0,1,4,31,146,1289,7736,85831,641302,8732989, 78432212,1270475155,13338831858,250740220345, 3013809363056,64512904742895,873589792390382, 20982459271174517,316070362138732172, 8418423492219771211,139628838506569935338, 4084524856346911809777] |