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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 10 |
| 4 | 24 |
| 5 | 70 |
| 6 | 276 |
| 7 | 820 |
| 8 | 2616 |
| 9 | 8702 |
| 10 | 27902 |
| 11 | 89500 |
| 12 | 291050 |
| 13 | 939222 |
| 14 | 3029950 |
| 15 | 9798606 |
| 16 | 31657182 |
| 17 | 102237766 |
| 18 | 330356240 |
| 19 | 1067310022 |
| 20 | 3447911968 |
| 21 | 11139391996 |
| 22 | 35988377472 |
| 23 | 116265759012 |
| 24 | 375619824338 |
| 25 | 1213515477460 |
| 26 | 3920484872552 |
| 27 | 12665878390278 |
[1,0,2,10,24,70,276,820,2616,8702,27902,89500, 291050,939222,3029950,9798606,31657182,102237766, 330356240,1067310022,3447911968,11139391996, 35988377472,116265759012,375619824338, 1213515477460,3920484872552,12665878390278] |