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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 10 |
| 3 | 40 |
| 4 | 172 |
| 5 | 728 |
| 6 | 3096 |
| 7 | 13152 |
| 8 | 55888 |
| 9 | 237472 |
| 10 | 1009056 |
| 11 | 4287616 |
| 12 | 18218688 |
| 13 | 77413760 |
| 14 | 328941952 |
| 15 | 1397720576 |
| 16 | 5939111168 |
| 17 | 25236118016 |
| 18 | 107231812096 |
| 19 | 455643039744 |
| 20 | 1936091311104 |
| 21 | 8226724075520 |
| 22 | 34956506765312 |
| 23 | 148535109967872 |
| 24 | 631146557100032 |
[1,2,10,40,172,728,3096,13152,55888,237472, 1009056,4287616,18218688,77413760,328941952, 1397720576,5939111168,25236118016,107231812096, 455643039744,1936091311104,8226724075520, 34956506765312,148535109967872,631146557100032] |