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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 13 |
| 2 | 104 |
| 3 | 637 |
| 4 | 3276 |
| 5 | 14808 |
| 6 | 60541 |
| 7 | 228124 |
| 8 | 803010 |
| 9 | 2667054 |
| 10 | 8422715 |
| 11 | 25446304 |
| 12 | 73907808 |
| 13 | 207209614 |
| 14 | 562673618 |
| 15 | 1484147681 |
| 16 | 3811882087 |
| 17 | 9553588317 |
| 18 | 23407932874 |
| 19 | 56161135485 |
| 20 | 132132608899 |
| 21 | 305240006266 |
| 22 | 693150485885 |
| 23 | 1548871015291 |
| 24 | 3408852663762 |
| 25 | 7395582677152 |
[1,13,104,637,3276,14808,60541,228124,803010, 2667054,8422715,25446304,73907808,207209614, 562673618,1484147681,3811882087,9553588317, 23407932874,56161135485,132132608899,305240006266, 693150485885,1548871015291,3408852663762, 7395582677152] |