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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 22 |
| 4 | 87 |
| 5 | 323 |
| 6 | 1342 |
| 7 | 5468 |
| 8 | 23419 |
| 9 | 100418 |
| 10 | 440643 |
| 11 | 1947254 |
| 12 | 8713746 |
| 13 | 39265051 |
| 14 | 178424429 |
| 15 | 815376294 |
| 16 | 3749149497 |
| 17 | 17318997226 |
| 18 | 80376437925 |
| 19 | 374471291983 |
| 20 | 1750996971807 |
| 21 | 8214029567976 |
| 22 | 38646789638674 |
| 23 | 182322472323533 |
| 24 | 862271866845863 |
| 25 | 4087275031494930 |
| 26 | 19415011169055886 |
| 27 | 92402575597208605 |
[1,2,7,22,87,323,1342,5468,23419,100418,440643, 1947254,8713746,39265051,178424429,815376294, 3749149497,17318997226,80376437925,374471291983, 1750996971807,8214029567976,38646789638674, 182322472323533,862271866845863,4087275031494930, 19415011169055886,92402575597208605] |