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| n | a(n) |
|---|---|
| 1 | 6 |
| 2 | 21 |
| 3 | 75 |
| 4 | 267 |
| 5 | 951 |
| 6 | 3328 |
| 7 | 11576 |
| 8 | 40309 |
| 9 | 140298 |
| 10 | 487872 |
| 11 | 1695490 |
| 12 | 5890943 |
| 13 | 20469215 |
| 14 | 71122969 |
| 15 | 247110741 |
| 16 | 858548734 |
| 17 | 2982886197 |
| 18 | 10363606865 |
| 19 | 36006690099 |
| 20 | 125099226783 |
| 21 | 434636165827 |
| 22 | 1510070809645 |
| 23 | 5246488474683 |
| 24 | 18228043608602 |
[6,21,75,267,951,3328,11576,40309,140298,487872, 1695490,5890943,20469215,71122969,247110741, 858548734,2982886197,10363606865,36006690099, 125099226783,434636165827,1510070809645, 5246488474683,18228043608602] |