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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 6 |
| 3 | 33 |
| 4 | 280 |
| 5 | 3185 |
| 6 | 46956 |
| 7 | 824593 |
| 8 | 16782872 |
| 9 | 387446193 |
| 10 | 10000154620 |
| 11 | 285312472621 |
| 12 | 8916105651300 |
| 13 | 302875136889793 |
| 14 | 11112007033351602 |
| 15 | 437893891702463085 |
| 16 | 18446744083262649616 |
| 17 | 827240261951698484129 |
| 18 | 39346408075791905146044 |
| 19 | 1978419655663922695962061 |
[0,1,6,33,280,3185,46956,824593,16782872, 387446193,10000154620,285312472621,8916105651300, 302875136889793,11112007033351602, 437893891702463085,18446744083262649616, 827240261951698484129,39346408075791905146044, 1978419655663922695962061] |