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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 6 |
| 4 | 30 |
| 5 | 146 |
| 6 | 719 |
| 7 | 3590 |
| 8 | 18283 |
| 9 | 94648 |
| 10 | 497757 |
| 11 | 2652898 |
| 12 | 14307845 |
| 13 | 77958746 |
| 14 | 428588051 |
| 15 | 2374676854 |
| 16 | 13247984959 |
| 17 | 74357762790 |
| 18 | 419604029622 |
| 19 | 2379243477538 |
| 20 | 13549087798391 |
| 21 | 77458553063930 |
| 22 | 444383895880897 |
| 23 | 2557639072274418 |
| 24 | 14763596994726379 |
| 25 | 85449948037167684 |
[1,6,30,146,719,3590,18283,94648,497757,2652898, 14307845,77958746,428588051,2374676854, 13247984959,74357762790,419604029622, 2379243477538,13549087798391,77458553063930, 444383895880897,2557639072274418, 14763596994726379,85449948037167684] |