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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 31 |
| 4 | 211 |
| 5 | 1841 |
| 6 | 18547 |
| 7 | 210664 |
| 8 | 2682657 |
| 9 | 37807531 |
| 10 | 581985596 |
| 11 | 9696297528 |
| 12 | 173702897000 |
| 13 | 3327063115248 |
| 14 | 67790086866271 |
| 15 | 1462900566163696 |
| 16 | 33310115601839624 |
| 17 | 797687851718024035 |
| 18 | 20032231443590167914 |
| 19 | 526189230537615409571 |
| 20 | 14423255501358439152231 |
[1,1,6,31,211,1841,18547,210664,2682657,37807531, 581985596,9696297528,173702897000,3327063115248, 67790086866271,1462900566163696,33310115601839624, 797687851718024035,20032231443590167914, 526189230537615409571,14423255501358439152231] |