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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 3 |
| 3 | 20 |
| 4 | 1 |
| 5 | 42 |
| 6 | 231 |
| 7 | 3432 |
| 8 | 12870 |
| 9 | 48620 |
| 10 | 16796 |
| 11 | 88179 |
| 12 | 117572 |
| 13 | 10400600 |
| 14 | 2111400 |
| 15 | 3447056 |
| 16 | 100180065 |
| 17 | 51857916 |
| 18 | 756261275 |
| 19 | 35345263800 |
| 20 | 68923264410 |
| 21 | 48932534040 |
| 22 | 420819792744 |
| 23 | 8233430727600 |
| 24 | 10749201227700 |
| 25 | 63205303218876 |
| 26 | 15997372030584 |
[1,2,3,20,1,42,231,3432,12870,48620,16796,88179, 117572,10400600,2111400,3447056,100180065, 51857916,756261275,35345263800,68923264410, 48932534040,420819792744,8233430727600, 10749201227700,63205303218876,15997372030584] |