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| n | a(n) |
|---|---|
| 1 | 20 |
| 2 | 400 |
| 3 | 5029 |
| 4 | 44803 |
| 5 | 308470 |
| 6 | 1738756 |
| 7 | 8350154 |
| 8 | 35158856 |
| 9 | 132595894 |
| 10 | 455284536 |
| 11 | 1441678804 |
| 12 | 4253578398 |
| 13 | 11791889562 |
| 14 | 30929283640 |
| 15 | 77204065141 |
| 16 | 184304047745 |
| 17 | 422556706314 |
| 18 | 933834642586 |
| 19 | 1995549087157 |
| 20 | 4134881948947 |
| 21 | 8327774224280 |
[20,400,5029,44803,308470,1738756,8350154, 35158856,132595894,455284536,1441678804, 4253578398,11791889562,30929283640,77204065141, 184304047745,422556706314,933834642586, 1995549087157,4134881948947,8327774224280] |