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| n | a(n) |
|---|---|
| 1 | 154 |
| 2 | 670 |
| 3 | 2900 |
| 4 | 12578 |
| 5 | 54530 |
| 6 | 236496 |
| 7 | 1025770 |
| 8 | 4449942 |
| 9 | 19307284 |
| 10 | 83782730 |
| 11 | 363623322 |
| 12 | 1578383808 |
| 13 | 6852296402 |
| 14 | 29752369022 |
| 15 | 129201632884 |
| 16 | 561144450002 |
| 17 | 2437478108882 |
| 18 | 10589252938544 |
| 19 | 46009511768922 |
| 20 | 199934061184966 |
[154,670,2900,12578,54530,236496,1025770,4449942, 19307284,83782730,363623322,1578383808,6852296402, 29752369022,129201632884,561144450002, 2437478108882,10589252938544,46009511768922, 199934061184966] |