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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 13 |
| 3 | 7 |
| 4 | 72 |
| 5 | 238 |
| 6 | 895 |
| 7 | 3335 |
| 8 | 13980 |
| 9 | 55889 |
| 10 | 230402 |
| 11 | 953813 |
| 12 | 3957108 |
| 13 | 16359243 |
| 14 | 67815820 |
| 15 | 280896101 |
| 16 | 1164014899 |
| 17 | 4823739307 |
| 18 | 19992787735 |
| 19 | 82860456229 |
| 20 | 343442251791 |
| 21 | 1423487855696 |
| 22 | 5900154785814 |
| 23 | 24455403244104 |
| 24 | 101365322534618 |
[0,13,7,72,238,895,3335,13980,55889,230402,953813, 3957108,16359243,67815820,280896101,1164014899, 4823739307,19992787735,82860456229,343442251791, 1423487855696,5900154785814,24455403244104, 101365322534618] |