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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 7 |
| 5 | 20 |
| 6 | 56 |
| 7 | 166 |
| 8 | 498 |
| 9 | 1530 |
| 10 | 4762 |
| 11 | 15022 |
| 12 | 47862 |
| 13 | 153859 |
| 14 | 498239 |
| 15 | 1623779 |
| 16 | 5321059 |
| 17 | 17520994 |
| 18 | 57937106 |
| 19 | 192304222 |
| 20 | 640446358 |
| 21 | 2139414409 |
| 22 | 7166431909 |
| 23 | 24065926653 |
| 24 | 81003492725 |
| 25 | 273229977460 |
| 26 | 923438683996 |
| 27 | 3126674842896 |
| 28 | 10604713671208 |
| 29 | 36025426127382 |
| 30 | 122566140787390 |
| 31 | 417584644921806 |
| 32 | 1424610537707166 |
| 33 | 4866239784751346 |
| 34 | 16642071212737394 |
| 35 | 56978489024931038 |
| 36 | 195289731964727862 |
| 37 | 670023314236521396 |
| 38 | 2301024202252503308 |
| 39 | 7909580344156028160 |
[1,1,3,7,20,56,166,498,1530,4762,15022,47862, 153859,498239,1623779,5321059,17520994,57937106, 192304222,640446358,2139414409,7166431909, 24065926653,81003492725,273229977460,923438683996, 3126674842896,10604713671208,36025426127382, 122566140787390,417584644921806,1424610537707166, 4866239784751346,16642071212737394, 56978489024931038,195289731964727862, 670023314236521396,2301024202252503308, 7909580344156028160] |