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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 7 |
| 3 | 57 |
| 4 | 484 |
| 5 | 4199 |
| 6 | 36938 |
| 7 | 328185 |
| 8 | 2937932 |
| 9 | 26457508 |
| 10 | 239414383 |
| 11 | 2175127695 |
| 12 | 19827974412 |
| 13 | 181266501290 |
| 14 | 1661241473220 |
| 15 | 15257624681145 |
| 16 | 140400178555644 |
| 17 | 1294141164447692 |
| 18 | 11946771748196428 |
| 19 | 110435320379615620 |
| 20 | 1022108852175416720 |
| 21 | 9470416604629933935 |
[1,1,7,57,484,4199,36938,328185,2937932,26457508, 239414383,2175127695,19827974412,181266501290, 1661241473220,15257624681145,140400178555644, 1294141164447692,11946771748196428, 110435320379615620,1022108852175416720, 9470416604629933935] |