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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 21 |
| 4 | 148 |
| 5 | 1078 |
| 6 | 7898 |
| 7 | 60843 |
| 8 | 486390 |
| 9 | 3969956 |
| 10 | 33123937 |
| 11 | 280486145 |
| 12 | 2411806083 |
[0,1,21,148,1078,7898,60843,486390,3969956, 33123937,280486145,2411806083] |