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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 6 |
| 5 | 4 |
| 6 | 30 |
| 7 | 15 |
| 8 | 140 |
| 9 | 56 |
| 10 | 630 |
| 11 | 210 |
| 12 | 2772 |
| 13 | 792 |
| 14 | 12012 |
| 15 | 3003 |
| 16 | 51480 |
| 17 | 11440 |
| 18 | 218790 |
| 19 | 43758 |
| 20 | 923780 |
| 21 | 167960 |
| 22 | 3879876 |
| 23 | 646646 |
| 24 | 16224936 |
| 25 | 2496144 |
| 26 | 67603900 |
| 27 | 9657700 |
| 28 | 280816200 |
| 29 | 37442160 |
| 30 | 1163381400 |
| 31 | 145422675 |
| 32 | 4808643120 |
| 33 | 565722720 |
| 34 | 19835652870 |
| 35 | 2203961430 |
[0,1,1,6,4,30,15,140,56,630,210,2772,792,12012, 3003,51480,11440,218790,43758,923780,167960, 3879876,646646,16224936,2496144,67603900,9657700, 280816200,37442160,1163381400,145422675, 4808643120,565722720,19835652870,2203961430] |