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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 7 |
| 2 | 36 |
| 3 | 165 |
| 4 | 715 |
| 5 | 3000 |
| 6 | 12376 |
| 7 | 50388 |
| 8 | 203490 |
| 9 | 817190 |
| 10 | 3268750 |
| 11 | 13037895 |
| 12 | 51895935 |
| 13 | 206253075 |
| 14 | 818809200 |
| 15 | 3247943125 |
| 16 | 12875774670 |
| 17 | 51021117810 |
| 18 | 202112640600 |
| 19 | 800472431850 |
| 20 | 3169870830000 |
| 21 | 12551759587422 |
| 22 | 49699896548176 |
[0,7,36,165,715,3000,12376,50388,203490,817190, 3268750,13037895,51895935,206253075,818809200, 3247943125,12875774670,51021117810,202112640600, 800472431850,3169870830000,12551759587422, 49699896548176] |