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| n | a(n) |
|---|---|
| 6 | 1 |
| 7 | 14 |
| 8 | 120 |
| 9 | 825 |
| 10 | 5005 |
| 11 | 28028 |
| 12 | 148512 |
| 13 | 755820 |
| 14 | 3730650 |
| 15 | 17978180 |
| 16 | 84987760 |
| 17 | 395482815 |
| 18 | 1816357725 |
| 19 | 8250123000 |
| 20 | 37119350400 |
| 21 | 165645101160 |
| 22 | 733919156190 |
| 23 | 3231337461300 |
| 24 | 14147884842000 |
| 25 | 61636377252450 |
| 26 | 267325773340626 |
| 27 | 1154761882042824 |
| 28 | 4969989654817600 |
[1,14,120,825,5005,28028,148512,755820,3730650, 17978180,84987760,395482815,1816357725,8250123000, 37119350400,165645101160,733919156190, 3231337461300,14147884842000,61636377252450, 267325773340626,1154761882042824,4969989654817600] |