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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 21 |
| 3 | 76 |
| 4 | 296 |
| 5 | 1004 |
| 6 | 3984 |
| 7 | 15556 |
| 8 | 60308 |
| 9 | 241016 |
| 10 | 959044 |
| 11 | 3834608 |
| 12 | 15311436 |
| 13 | 61288052 |
| 14 | 245072724 |
| 15 | 980065360 |
[1,5,21,76,296,1004,3984,15556,60308,241016, 959044,3834608,15311436,61288052,245072724, 980065360] |