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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 5 |
| 6 | 13 |
| 7 | 43 |
| 8 | 116 |
| 9 | 335 |
| 10 | 920 |
| 11 | 2591 |
| 12 | 7173 |
| 13 | 20125 |
| 14 | 56260 |
| 15 | 158333 |
| 16 | 446098 |
| 17 | 1262225 |
| 18 | 3579227 |
| 19 | 10181479 |
| 20 | 29028405 |
| 21 | 82968695 |
| 22 | 237634700 |
| 23 | 682014587 |
| 24 | 1960951980 |
| 25 | 5647919640 |
| 26 | 16292680600 |
| 27 | 47069103545 |
| 28 | 136166476875 |
| 29 | 394418199725 |
| 30 | 1143821408316 |
| 31 | 3320790074371 |
[0,0,0,1,5,13,43,116,335,920,2591,7173,20125, 56260,158333,446098,1262225,3579227,10181479, 29028405,82968695,237634700,682014587,1960951980, 5647919640,16292680600,47069103545,136166476875, 394418199725,1143821408316,3320790074371] |