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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 15 |
| 3 | 126 |
| 4 | 715 |
| 5 | 3060 |
| 6 | 10626 |
| 7 | 31465 |
| 8 | 82251 |
| 9 | 194580 |
| 10 | 424270 |
| 11 | 864501 |
| 12 | 1663740 |
| 13 | 3049501 |
| 14 | 5359095 |
| 15 | 9078630 |
| 16 | 14891626 |
| 17 | 23738715 |
| 18 | 36890001 |
| 19 | 56031760 |
| 20 | 83369265 |
| 21 | 121747626 |
| 22 | 174792640 |
| 23 | 247073751 |
| 24 | 344291325 |
| 25 | 473490550 |
| 26 | 643304376 |
[1,15,126,715,3060,10626,31465,82251,194580, 424270,864501,1663740,3049501,5359095,9078630, 14891626,23738715,36890001,56031760,83369265, 121747626,174792640,247073751,344291325,473490550, 643304376] |