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| n | a(n) |
|---|---|
| 1 | 6 |
| 2 | 33 |
| 3 | 127 |
| 4 | 700 |
| 5 | 3175 |
| 6 | 15541 |
| 7 | 74736 |
| 8 | 358341 |
| 9 | 1729617 |
| 10 | 8308924 |
| 11 | 40006463 |
| 12 | 192481249 |
| 13 | 926168176 |
| 14 | 4456879585 |
| 15 | 21445119255 |
| 16 | 103193473908 |
| 17 | 496552428929 |
| 18 | 2389355832929 |
| 19 | 11497320733428 |
| 20 | 55323763675221 |
| 21 | 266211857683333 |
[6,33,127,700,3175,15541,74736,358341,1729617, 8308924,40006463,192481249,926168176,4456879585, 21445119255,103193473908,496552428929, 2389355832929,11497320733428,55323763675221, 266211857683333] |