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| n | a(n) |
|---|---|
| 0 | 20 |
| 1 | 21 |
| 2 | 41 |
| 3 | 62 |
| 4 | 227 |
| 5 | 516 |
| 6 | 3323 |
| 7 | 7162 |
| 8 | 24809 |
| 9 | 31971 |
| 10 | 56780 |
| 11 | 88751 |
| 12 | 3606820 |
| 13 | 3695571 |
| 14 | 7302391 |
| 15 | 10997962 |
| 16 | 40296277 |
| 17 | 91590516 |
| 18 | 589839373 |
| 19 | 1271269262 |
| 20 | 4403647159 |
| 21 | 5674916421 |
| 22 | 10078563580 |
| 23 | 15753480001 |
| 24 | 640217763620 |
| 25 | 655971243621 |
| 26 | 1296189007241 |
[20,21,41,62,227,516,3323,7162,24809,31971,56780, 88751,3606820,3695571,7302391,10997962,40296277, 91590516,589839373,1271269262,4403647159, 5674916421,10078563580,15753480001,640217763620, 655971243621,1296189007241] |