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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 3 |
| 3 | 20 |
| 4 | 139 |
| 5 | 1069 |
| 6 | 8747 |
| 7 | 74114 |
| 8 | 641594 |
| 9 | 5661135 |
| 10 | 50653546 |
| 11 | 458352691 |
| 12 | 4185483176 |
| 13 | 38510936699 |
| 14 | 356622729564 |
| 15 | 3320632228693 |
| 16 | 31067060521057 |
| 17 | 291869049531878 |
| 18 | 2752144407792176 |
| 19 | 26035873192178041 |
| 20 | 247025281876786013 |
| 21 | 2349914303292170310 |
| 22 | 22407593754131275705 |
[0,3,20,139,1069,8747,74114,641594,5661135, 50653546,458352691,4185483176,38510936699, 356622729564,3320632228693,31067060521057, 291869049531878,2752144407792176, 26035873192178041,247025281876786013, 2349914303292170310,22407593754131275705] |