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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 7 |
| 4 | 50 |
| 5 | 481 |
| 6 | 5667 |
| 7 | 78058 |
| 8 | 1238295 |
| 9 | 22314627 |
| 10 | 451354476 |
| 11 | 10148011215 |
| 12 | 251584513215 |
| 13 | 6831141750512 |
| 14 | 201976943666357 |
| 15 | 6470392653260939 |
| 16 | 223595676728884394 |
| 17 | 8302299221314559877 |
| 18 | 330075531021130110015 |
| 19 | 14006780163088113914026 |
| 20 | 632606447496264724088803 |
[1,0,1,7,50,481,5667,78058,1238295,22314627, 451354476,10148011215,251584513215,6831141750512, 201976943666357,6470392653260939, 223595676728884394,8302299221314559877, 330075531021130110015,14006780163088113914026, 632606447496264724088803] |