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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 8 |
| 3 | 54 |
| 4 | 460 |
| 5 | 4361 |
| 6 | 43988 |
| 7 | 462580 |
| 8 | 5014252 |
| 9 | 55624944 |
| 10 | 628432101 |
| 11 | 7205500484 |
| 12 | 83632219892 |
| 13 | 980710882430 |
| 14 | 11601345881748 |
| 15 | 138278231052451 |
| 16 | 1659037424218780 |
| 17 | 20020306637339944 |
| 18 | 242835190201382648 |
| 19 | 2958961154058610552 |
| 20 | 36203518795424475661 |
[1,2,8,54,460,4361,43988,462580,5014252,55624944, 628432101,7205500484,83632219892,980710882430, 11601345881748,138278231052451,1659037424218780, 20020306637339944,242835190201382648, 2958961154058610552,36203518795424475661] |