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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 14 |
| 4 | 59 |
| 5 | 295 |
| 6 | 1770 |
| 7 | 12396 |
| 8 | 99171 |
| 9 | 892540 |
| 10 | 8925407 |
| 11 | 98179485 |
| 12 | 1178153825 |
| 13 | 15315999732 |
| 14 | 214423996260 |
| 15 | 3216359943912 |
| 16 | 51461759102607 |
| 17 | 874849904744335 |
| 18 | 15747298285398037 |
| 19 | 299198667422562716 |
| 20 | 5983973348451254333 |
[2,4,14,59,295,1770,12396,99171,892540,8925407, 98179485,1178153825,15315999732,214423996260, 3216359943912,51461759102607,874849904744335, 15747298285398037,299198667422562716, 5983973348451254333] |