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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 19 |
| 4 | 69 |
| 5 | 263 |
| 6 | 1044 |
| 7 | 4240 |
| 8 | 17595 |
| 9 | 74391 |
| 10 | 318493 |
| 11 | 1378895 |
| 12 | 6022039 |
| 13 | 26520440 |
| 14 | 117549906 |
| 15 | 524068965 |
| 16 | 2348103782 |
| 17 | 10568464412 |
| 18 | 47754218422 |
| 19 | 216537083286 |
| 20 | 984983798215 |
| 21 | 4493317804295 |
| 22 | 20550859759855 |
| 23 | 94213221969645 |
| 24 | 432845203438126 |
| 25 | 1992563341419802 |
| 26 | 9189311952508953 |
| 27 | 42450573153408853 |
[1,2,6,19,69,263,1044,4240,17595,74391,318493, 1378895,6022039,26520440,117549906,524068965, 2348103782,10568464412,47754218422,216537083286, 984983798215,4493317804295,20550859759855, 94213221969645,432845203438126,1992563341419802, 9189311952508953,42450573153408853] |