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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 4 |
| 3 | 28 |
| 4 | 676 |
| 5 | 72852 |
| 6 | 26193924 |
| 7 | 31747280900 |
| 8 | 124891129720900 |
| 9 | 1596519898829489564 |
| 10 | 66137923505214401888644 |
| 11 | 8881717991453403420376233852 |
| 12 | 3865789910670398372168483012783044 |
[0,4,28,676,72852,26193924,31747280900, 124891129720900,1596519898829489564, 66137923505214401888644, 8881717991453403420376233852, 3865789910670398372168483012783044] |