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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 56 |
| 3 | 490 |
| 4 | 6842 |
| 5 | 124754 |
| 6 | 831820 |
| 7 | 13848650 |
| 8 | 133230930 |
| 9 | 214481126 |
| 10 | 271248950 |
| 11 | 541946240 |
| 12 | 851376628 |
| 13 | 5964539504 |
| 14 | 11097645016 |
| 15 | 37027355200 |
| 16 | 45060624582 |
| 17 | 142798995930 |
| 18 | 207890420102 |
| 19 | 625846753120 |
| 20 | 1820701100652 |
| 21 | 3068829878530 |
| 22 | 37561133582570 |
| 23 | 114540884553038 |
[2,56,490,6842,124754,831820,13848650,133230930, 214481126,271248950,541946240,851376628, 5964539504,11097645016,37027355200,45060624582, 142798995930,207890420102,625846753120, 1820701100652,3068829878530,37561133582570, 114540884553038] |