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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 93 |
| 5 | 816 |
| 6 | 9264 |
| 7 | 122028 |
| 8 | 1863849 |
| 9 | 32001504 |
| 10 | 614224272 |
| 11 | 12989299596 |
| 12 | 300599511744 |
| 13 | 7550646317520 |
| 14 | 204694926767040 |
| 15 | 5955892801274796 |
| 16 | 185160666502244433 |
| 17 | 6125200081143892800 |
| 18 | 214838236392631067424 |
| 19 | 7963817560398871790604 |
| 20 | 311101474513327693885056 |
[1,3,12,93,816,9264,122028,1863849,32001504, 614224272,12989299596,300599511744,7550646317520, 204694926767040,5955892801274796, 185160666502244433,6125200081143892800, 214838236392631067424,7963817560398871790604, 311101474513327693885056] |