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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 6 |
| 5 | 16 |
| 6 | 28 |
| 7 | 120 |
| 8 | 264 |
| 9 | 576 |
| 10 | 2784 |
| 11 | 11040 |
| 12 | 37440 |
| 13 | 204672 |
| 14 | 679680 |
| 15 | 2511360 |
| 16 | 15655680 |
| 17 | 52945920 |
| 18 | 232796160 |
| 19 | 2456801280 |
| 20 | 11867627520 |
| 21 | 97875025920 |
| 22 | 576737280000 |
| 23 | 4012233523200 |
| 24 | 20013325516800 |
| 25 | 215802239385600 |
| 26 | 1778700504268800 |
| 27 | 9687506721177600 |
| 28 | 88613303353344000 |
| 29 | 448250987623219200 |
[1,2,4,6,16,28,120,264,576,2784,11040,37440, 204672,679680,2511360,15655680,52945920,232796160, 2456801280,11867627520,97875025920,576737280000, 4012233523200,20013325516800,215802239385600, 1778700504268800,9687506721177600, 88613303353344000,448250987623219200] |