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| n | a(n) |
|---|---|
| 1 | 1640 |
| 2 | 5728 |
| 3 | 27168 |
| 4 | 283728 |
| 5 | 1236432 |
| 6 | 9042600 |
| 7 | 95322432 |
| 8 | 419146392 |
| 9 | 3065437344 |
| 10 | 32314300392 |
| 11 | 142090622832 |
| 12 | 1039183255560 |
| 13 | 10954547828832 |
| 14 | 48168721135992 |
| 15 | 352283123630784 |
| 16 | 3713591713969992 |
| 17 | 16329196465097232 |
| 18 | 119423978910831720 |
[1640,5728,27168,283728,1236432,9042600,95322432, 419146392,3065437344,32314300392,142090622832, 1039183255560,10954547828832,48168721135992, 352283123630784,3713591713969992, 16329196465097232,119423978910831720] |