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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 20 |
| 4 | 46 |
| 5 | 308 |
| 6 | 990 |
| 7 | 4679 |
| 8 | 26963 |
| 9 | 153319 |
| 10 | 1074940 |
| 11 | 8523830 |
| 12 | 71415327 |
[1,7,20,46,308,990,4679,26963,153319,1074940, 8523830,71415327] |