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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 26 |
| 4 | 134 |
| 5 | 702 |
| 6 | 3642 |
| 7 | 18916 |
| 8 | 99078 |
| 9 | 523448 |
| 10 | 2783406 |
| 11 | 14870418 |
| 12 | 79743002 |
| 13 | 428987236 |
| 14 | 2314194840 |
| 15 | 12514276476 |
| 16 | 67815709958 |
| 17 | 368183248722 |
| 18 | 2002240199040 |
| 19 | 10904629019548 |
| 20 | 59468066955534 |
| 21 | 324698112501166 |
| 22 | 1774806572174862 |
| 23 | 9710825272099992 |
| 24 | 53181284133726618 |
[1,2,6,26,134,702,3642,18916,99078,523448,2783406, 14870418,79743002,428987236,2314194840, 12514276476,67815709958,368183248722, 2002240199040,10904629019548,59468066955534, 324698112501166,1774806572174862,9710825272099992, 53181284133726618] |