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| n | a(n) |
|---|---|
| 1 | 15 |
| 2 | 22 |
| 3 | 208 |
| 4 | 1531 |
| 5 | 8964 |
| 6 | 44816 |
| 7 | 220182 |
| 8 | 1116208 |
| 9 | 5697556 |
| 10 | 28354294 |
| 11 | 135630422 |
| 12 | 623221049 |
| 13 | 2761665622 |
| 14 | 11842133497 |
| 15 | 49237357701 |
| 16 | 198775751684 |
| 17 | 780253085746 |
| 18 | 2982381614057 |
| 19 | 11117260746432 |
| 20 | 40470971856226 |
| 21 | 144060818799022 |
[15,22,208,1531,8964,44816,220182,1116208,5697556, 28354294,135630422,623221049,2761665622, 11842133497,49237357701,198775751684,780253085746, 2982381614057,11117260746432,40470971856226, 144060818799022] |