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| n | a(n) |
|---|---|
| 4 | 1 |
| 5 | 4 |
| 6 | 10 |
| 7 | 22 |
| 8 | 55 |
| 9 | 192 |
| 10 | 702 |
| 11 | 3882 |
| 12 | 23422 |
| 13 | 155527 |
| 14 | 1170160 |
| 15 | 10636314 |
| 16 | 113496925 |
| 17 | 1456900734 |
| 18 | 21993819116 |
[1,4,10,22,55,192,702,3882,23422,155527,1170160, 10636314,113496925,1456900734,21993819116] |