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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 21 |
| 4 | 53 |
| 5 | 197 |
| 6 | 661 |
| 7 | 2085 |
| 8 | 7093 |
| 9 | 23365 |
| 10 | 76757 |
| 11 | 255333 |
| 12 | 842741 |
| 13 | 2785157 |
| 14 | 9220117 |
| 15 | 30473637 |
| 16 | 100775989 |
| 17 | 333311941 |
| 18 | 1102099541 |
| 19 | 3644659173 |
| 20 | 12052800629 |
| 21 | 39856631813 |
| 22 | 131803744405 |
| 23 | 435863879205 |
| 24 | 1441358438581 |
| 25 | 4766458888261 |
| 26 | 15762259193045 |
| 27 | 52124396009061 |
[1,1,5,21,53,197,661,2085,7093,23365,76757,255333, 842741,2785157,9220117,30473637,100775989, 333311941,1102099541,3644659173,12052800629, 39856631813,131803744405,435863879205, 1441358438581,4766458888261,15762259193045, 52124396009061] |