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| n | a(n) |
|---|---|
| 1 | 12 |
| 2 | 144 |
| 3 | 420 |
| 4 | 2508 |
| 5 | 10080 |
| 6 | 50052 |
| 7 | 221340 |
| 8 | 1042416 |
| 9 | 4742628 |
| 10 | 21989868 |
| 11 | 100900800 |
| 12 | 465657348 |
| 13 | 2142175548 |
| 14 | 9872120016 |
| 15 | 45450619620 |
| 16 | 209366048652 |
| 17 | 964140982560 |
| 18 | 4440671206788 |
| 19 | 20451041895900 |
| 20 | 94190120555184 |
| 21 | 433792784654052 |
[12,144,420,2508,10080,50052,221340,1042416, 4742628,21989868,100900800,465657348,2142175548, 9872120016,45450619620,209366048652,964140982560, 4440671206788,20451041895900,94190120555184, 433792784654052] |