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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 5 |
| 6 | 3 |
| 7 | 10 |
| 8 | 40 |
| 9 | 51 |
| 10 | 21 |
| 11 | 122 |
| 12 | 644 |
| 13 | 1236 |
| 14 | 1029 |
| 15 | 315 |
| 16 | 3346 |
| 17 | 21496 |
| 18 | 54060 |
| 19 | 66780 |
| 20 | 40635 |
| 21 | 9765 |
| 22 | 196082 |
| 23 | 1471460 |
| 24 | 4527228 |
| 25 | 7328580 |
| 26 | 6596100 |
| 27 | 3134565 |
| 28 | 615195 |
[1,1,1,2,5,3,10,40,51,21,122,644,1236,1029,315, 3346,21496,54060,66780,40635,9765,196082,1471460, 4527228,7328580,6596100,3134565,615195] |