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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 26 |
| 4 | 370 |
| 5 | 7334 |
| 6 | 186468 |
| 7 | 5787144 |
| 8 | 212100208 |
| 9 | 8964974016 |
| 10 | 429304991880 |
| 11 | 22971063265776 |
| 12 | 1358260804832160 |
| 13 | 87949592273821680 |
| 14 | 6189420503357272608 |
| 15 | 470384337802047909120 |
| 16 | 38393707193347187344896 |
| 17 | 3349704214386311986028160 |
[0,1,3,26,370,7334,186468,5787144,212100208, 8964974016,429304991880,22971063265776, 1358260804832160,87949592273821680, 6189420503357272608,470384337802047909120, 38393707193347187344896,3349704214386311986028160] |