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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 40 |
| 3 | 136 |
| 4 | 6400 |
| 5 | 71944 |
| 6 | 1866192 |
| 7 | 32292680 |
| 8 | 679262904 |
| 9 | 13081009496 |
| 10 | 262832968576 |
| 11 | 5182051255656 |
| 12 | 103098503270144 |
| 13 | 2042906229701640 |
| 14 | 40558460980862344 |
| 15 | 804524501026875864 |
| 16 | 15965241050999242720 |
| 17 | 316760803542953380040 |
[0,40,136,6400,71944,1866192,32292680,679262904, 13081009496,262832968576,5182051255656, 103098503270144,2042906229701640, 40558460980862344,804524501026875864, 15965241050999242720,316760803542953380040] |