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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 106 |
| 6 | 496 |
| 7 | 2428 |
| 8 | 12288 |
| 9 | 63762 |
| 10 | 337392 |
| 11 | 1813628 |
| 12 | 9876096 |
| 13 | 54365876 |
| 14 | 302037408 |
| 15 | 1691327224 |
| 16 | 9536234496 |
| 17 | 54093070626 |
| 18 | 308474110000 |
| 19 | 1767481876540 |
| 20 | 10170367611008 |
| 21 | 58746459504884 |
| 22 | 340513035730944 |
| 23 | 1979964903739992 |
| 24 | 11546094361266176 |
| 25 | 67509252360531940 |
[1,2,6,24,106,496,2428,12288,63762,337392,1813628, 9876096,54365876,302037408,1691327224,9536234496, 54093070626,308474110000,1767481876540, 10170367611008,58746459504884,340513035730944, 1979964903739992,11546094361266176, 67509252360531940] |