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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 5 |
| 6 | 14 |
| 7 | 42 |
| 8 | 136 |
| 9 | 479 |
| 10 | 1825 |
| 11 | 7433 |
| 12 | 32053 |
| 13 | 145608 |
| 14 | 695081 |
| 15 | 3479117 |
| 16 | 18209842 |
| 17 | 99373513 |
| 18 | 563920590 |
| 19 | 3320674902 |
| 20 | 20255823092 |
| 21 | 127799984935 |
| 22 | 832807892861 |
| 23 | 5597481205009 |
| 24 | 38753768384761 |
| 25 | 276057156622776 |
| 26 | 2021100095469577 |
| 27 | 15193591060371577 |
[1,0,1,1,2,5,14,42,136,479,1825,7433,32053,145608, 695081,3479117,18209842,99373513,563920590, 3320674902,20255823092,127799984935,832807892861, 5597481205009,38753768384761,276057156622776, 2021100095469577,15193591060371577] |