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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 6 |
| 5 | 30 |
| 6 | 20 |
| 7 | 140 |
| 8 | 70 |
| 9 | 630 |
| 10 | 252 |
| 11 | 2772 |
| 12 | 924 |
| 13 | 12012 |
| 14 | 3432 |
| 15 | 51480 |
| 16 | 12870 |
| 17 | 218790 |
| 18 | 48620 |
| 19 | 923780 |
| 20 | 184756 |
| 21 | 3879876 |
| 22 | 705432 |
| 23 | 16224936 |
| 24 | 2704156 |
| 25 | 67603900 |
| 26 | 10400600 |
| 27 | 280816200 |
| 28 | 40116600 |
| 29 | 1163381400 |
| 30 | 155117520 |
| 31 | 4808643120 |
| 32 | 601080390 |
| 33 | 19835652870 |
| 34 | 2333606220 |
[1,1,2,6,6,30,20,140,70,630,252,2772,924,12012, 3432,51480,12870,218790,48620,923780,184756, 3879876,705432,16224936,2704156,67603900,10400600, 280816200,40116600,1163381400,155117520, 4808643120,601080390,19835652870,2333606220] |