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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 12 |
| 4 | 44 |
| 5 | 160 |
| 6 | 635 |
| 7 | 2520 |
| 8 | 10374 |
| 9 | 43134 |
| 10 | 183372 |
| 11 | 785862 |
| 12 | 3413850 |
| 13 | 14943786 |
| 14 | 66054417 |
| 15 | 293780916 |
| 16 | 1315917746 |
| 17 | 5925586810 |
| 18 | 26832235430 |
| 19 | 122037157814 |
| 20 | 557522216602 |
| 21 | 2556606994682 |
| 22 | 11767063971676 |
| 23 | 54332854794374 |
| 24 | 251652806269006 |
| 25 | 1168810615051590 |
| 26 | 5442994681797090 |
| 27 | 25408401050126850 |
[1,1,4,12,44,160,635,2520,10374,43134,183372, 785862,3413850,14943786,66054417,293780916, 1315917746,5925586810,26832235430,122037157814, 557522216602,2556606994682,11767063971676, 54332854794374,251652806269006,1168810615051590, 5442994681797090,25408401050126850] |