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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 15 |
| 3 | 97 |
| 4 | 717 |
| 5 | 5736 |
| 6 | 48340 |
| 7 | 422688 |
| 8 | 3799080 |
| 9 | 34881159 |
| 10 | 325750143 |
| 11 | 3084634305 |
| 12 | 29548452297 |
| 13 | 285825135183 |
| 14 | 2787990695931 |
| 15 | 27391816756281 |
| 16 | 270828413410413 |
| 17 | 2692692976016352 |
| 18 | 26904718314949776 |
| 19 | 270017389769189136 |
| 20 | 2720718671661444780 |
| 21 | 27513054621821846074 |
[1,3,15,97,717,5736,48340,422688,3799080,34881159, 325750143,3084634305,29548452297,285825135183, 2787990695931,27391816756281,270828413410413, 2692692976016352,26904718314949776, 270017389769189136,2720718671661444780, 27513054621821846074] |