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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 24 |
| 3 | 98 |
| 4 | 392 |
| 5 | 1570 |
| 6 | 6280 |
| 7 | 25122 |
| 8 | 100488 |
| 9 | 401954 |
| 10 | 1607816 |
| 11 | 6431266 |
| 12 | 25725064 |
| 13 | 102900258 |
| 14 | 411601032 |
| 15 | 1646404130 |
| 16 | 6585616520 |
| 17 | 26342466082 |
| 18 | 105369864328 |
| 19 | 421479457314 |
| 20 | 1685917829256 |
| 21 | 6743671317026 |
| 22 | 26974685268104 |
[1,6,24,98,392,1570,6280,25122,100488,401954, 1607816,6431266,25725064,102900258,411601032, 1646404130,6585616520,26342466082,105369864328, 421479457314,1685917829256,6743671317026, 26974685268104] |