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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 21 |
| 2 | 61 |
| 3 | 141 |
| 4 | 377 |
| 5 | 1001 |
| 6 | 2737 |
| 7 | 7553 |
| 8 | 21073 |
| 9 | 59217 |
| 10 | 167441 |
| 11 | 475793 |
| 12 | 1357637 |
| 13 | 3887541 |
| 14 | 11165509 |
| 15 | 32152901 |
| 16 | 92802433 |
| 17 | 268398401 |
| 18 | 777651553 |
| 19 | 2256800033 |
| 20 | 6558953917 |
| 21 | 19087539437 |
| 22 | 55614451789 |
| 23 | 162219429293 |
| 24 | 473648632141 |
[1,21,61,141,377,1001,2737,7553,21073,59217, 167441,475793,1357637,3887541,11165509,32152901, 92802433,268398401,777651553,2256800033, 6558953917,19087539437,55614451789,162219429293, 473648632141] |