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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 2 |
| 5 | 5 |
| 6 | 18 |
| 7 | 43 |
| 8 | 126 |
| 9 | 339 |
| 10 | 946 |
| 11 | 2591 |
| 12 | 7254 |
| 13 | 20125 |
| 14 | 56450 |
| 15 | 158355 |
| 16 | 446618 |
| 17 | 1262225 |
| 18 | 3580686 |
| 19 | 10181479 |
| 20 | 29032254 |
| 21 | 82968843 |
| 22 | 237645250 |
| 23 | 682014587 |
| 24 | 1960981598 |
| 25 | 5647919645 |
| 26 | 16292761730 |
| 27 | 47069104613 |
| 28 | 136166703562 |
| 29 | 394418199725 |
| 30 | 1143822046786 |
| 31 | 3320790074371 |
[0,0,1,2,5,18,43,126,339,946,2591,7254,20125, 56450,158355,446618,1262225,3580686,10181479, 29032254,82968843,237645250,682014587,1960981598, 5647919645,16292761730,47069104613,136166703562, 394418199725,1143822046786,3320790074371] |