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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 45 |
| 4 | 508 |
| 5 | 7225 |
| 6 | 126306 |
| 7 | 2606065 |
| 8 | 62075952 |
| 9 | 1675774089 |
| 10 | 50565938050 |
| 11 | 1686510607111 |
| 12 | 61609858744248 |
| 13 | 2446470026497705 |
| 14 | 104922088624078194 |
| 15 | 4833250468667819325 |
| 16 | 238004208840601580416 |
| 17 | 12476420334546637657489 |
| 18 | 693675026024580055139778 |
[1,1,6,45,508,7225,126306,2606065,62075952, 1675774089,50565938050,1686510607111, 61609858744248,2446470026497705, 104922088624078194,4833250468667819325, 238004208840601580416,12476420334546637657489, 693675026024580055139778] |