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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 35 |
| 5 | 147 |
| 6 | 805 |
| 7 | 5399 |
| 8 | 42273 |
| 9 | 375787 |
| 10 | 3728261 |
| 11 | 40788255 |
| 12 | 487539769 |
| 13 | 6319430483 |
| 14 | 88272658797 |
| 15 | 1321745733511 |
| 16 | 21117967813025 |
| 17 | 358591883025339 |
| 18 | 6448525343069653 |
| 19 | 122424951294889967 |
| 20 | 2446864618294774281 |
| 21 | 51354975368171586595 |
| 22 | 1129258990476358286909 |
[1,1,4,11,35,147,805,5399,42273,375787,3728261, 40788255,487539769,6319430483,88272658797, 1321745733511,21117967813025,358591883025339, 6448525343069653,122424951294889967, 2446864618294774281,51354975368171586595, 1129258990476358286909] |