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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 10 |
| 4 | 23 |
| 5 | 82 |
| 6 | 236 |
| 7 | 730 |
| 8 | 2156 |
| 9 | 6571 |
| 10 | 19604 |
| 11 | 59050 |
| 12 | 176918 |
| 13 | 531442 |
| 14 | 1593596 |
| 15 | 4783060 |
| 16 | 14346689 |
| 17 | 43046722 |
| 18 | 129133838 |
| 19 | 387420490 |
| 20 | 1162241726 |
| 21 | 3486785140 |
| 22 | 10460294156 |
| 23 | 31381059610 |
| 24 | 94143003584 |
| 25 | 282429536563 |
| 26 | 847288078004 |
| 27 | 2541865834900 |
| 28 | 7625595889958 |
[1,2,10,23,82,236,730,2156,6571,19604,59050, 176918,531442,1593596,4783060,14346689,43046722, 129133838,387420490,1162241726,3486785140, 10460294156,31381059610,94143003584,282429536563, 847288078004,2541865834900,7625595889958] |