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| n | a(n) |
|---|---|
| 1 | 15 |
| 2 | 35 |
| 3 | 269 |
| 4 | 1688 |
| 5 | 8964 |
| 6 | 44736 |
| 7 | 219216 |
| 8 | 1062133 |
| 9 | 5046678 |
| 10 | 23361295 |
| 11 | 105246826 |
| 12 | 462379361 |
| 13 | 1984693730 |
| 14 | 8329188237 |
| 15 | 34174571720 |
| 16 | 137072090506 |
| 17 | 537533392034 |
| 18 | 2061741321158 |
| 19 | 7738348853856 |
| 20 | 28437341923159 |
| 21 | 102381325106959 |
[15,35,269,1688,8964,44736,219216,1062133,5046678, 23361295,105246826,462379361,1984693730, 8329188237,34174571720,137072090506,537533392034, 2061741321158,7738348853856,28437341923159, 102381325106959] |