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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 24 |
| 4 | 228 |
| 5 | 3936 |
| 6 | 132624 |
| 7 | 8762040 |
| 8 | 1156532424 |
| 9 | 306700450536 |
| 10 | 164818597404924 |
| 11 | 180360080611682424 |
| 12 | 403600060221250880496 |
| 13 | 1853096813379189131728692 |
| 14 | 17504763708306471241857275208 |
[1,6,24,228,3936,132624,8762040,1156532424, 306700450536,164818597404924,180360080611682424, 403600060221250880496,1853096813379189131728692, 17504763708306471241857275208] |