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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 4 |
| 3 | 10 |
| 4 | 27 |
| 5 | 72 |
| 6 | 188 |
| 7 | 493 |
| 8 | 1292 |
| 9 | 3382 |
| 10 | 8855 |
| 11 | 23184 |
| 12 | 60696 |
| 13 | 158905 |
| 14 | 416020 |
| 15 | 1089154 |
| 16 | 2851443 |
| 17 | 7465176 |
| 18 | 19544084 |
| 19 | 51167077 |
| 20 | 133957148 |
| 21 | 350704366 |
| 22 | 918155951 |
| 23 | 2403763488 |
| 24 | 6293134512 |
| 25 | 16475640049 |
| 26 | 43133785636 |
| 27 | 112925716858 |
| 28 | 295643364939 |
| 29 | 774004377960 |
[0,1,4,10,27,72,188,493,1292,3382,8855,23184, 60696,158905,416020,1089154,2851443,7465176, 19544084,51167077,133957148,350704366,918155951, 2403763488,6293134512,16475640049,43133785636, 112925716858,295643364939,774004377960] |