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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 73 |
| 6 | 239 |
| 7 | 734 |
| 8 | 2134 |
| 9 | 5934 |
| 10 | 15918 |
| 11 | 41470 |
| 12 | 105470 |
| 13 | 262910 |
| 14 | 644350 |
| 15 | 1556478 |
| 16 | 3713022 |
| 17 | 8761342 |
| 18 | 20475902 |
| 19 | 47448062 |
| 20 | 109117438 |
| 21 | 249233406 |
| 22 | 565772286 |
| 23 | 1277165566 |
| 24 | 2868379646 |
| 25 | 6412042238 |
| 26 | 14272167934 |
| 27 | 31641829374 |
| 28 | 69893881854 |
| 29 | 153863847934 |
| 30 | 337641471998 |
[1,2,6,21,73,239,734,2134,5934,15918,41470,105470, 262910,644350,1556478,3713022,8761342,20475902, 47448062,109117438,249233406,565772286,1277165566, 2868379646,6412042238,14272167934,31641829374, 69893881854,153863847934,337641471998] |