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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 16 |
| 5 | 90 |
| 6 | 636 |
| 7 | 5712 |
| 8 | 34336 |
| 9 | 537282 |
| 10 | 5941780 |
| 11 | 99729146 |
| 12 | 1049982792 |
| 13 | 23200347040 |
| 14 | 293841338896 |
| 15 | 5712436923000 |
| 16 | 68827002466176 |
| 17 | 2844850573581890 |
| 18 | 53069160498788772 |
| 19 | 1545326270301621838 |
| 20 | 26021954987946879560 |
| 21 | 1020860369624228471394 |
| 22 | 19905401189634441143740 |
| 23 | 605270985059438427438138 |
| 24 | 11141784565490367848976336 |
| 25 | 621465511993167908247508400 |
| 26 | 14470690420043042111787089216 |
| 27 | 548187222712632324159956010732 |
| 28 | 11881058908943228840652007583056 |
[1,2,6,16,90,636,5712,34336,537282,5941780, 99729146,1049982792,23200347040,293841338896, 5712436923000,68827002466176,2844850573581890, 53069160498788772,1545326270301621838, 26021954987946879560,1020860369624228471394, 19905401189634441143740,605270985059438427438138, 11141784565490367848976336, 621465511993167908247508400, 14470690420043042111787089216, 548187222712632324159956010732, 11881058908943228840652007583056] |