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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 9 |
| 4 | 88 |
| 5 | 1104 |
| 6 | 15772 |
| 7 | 241582 |
| 8 | 3869852 |
| 9 | 63689650 |
| 10 | 1065023018 |
| 11 | 17948615155 |
| 12 | 303219868652 |
| 13 | 5116273886322 |
| 14 | 86004191773864 |
| 15 | 1437703756689091 |
| 16 | 23869446608034827 |
| 17 | 393225674878151704 |
| 18 | 6423761195925513669 |
| 19 | 104014146020398166139 |
| 20 | 1668870762057827073994 |
[1,1,2,9,88,1104,15772,241582,3869852,63689650, 1065023018,17948615155,303219868652,5116273886322, 86004191773864,1437703756689091,23869446608034827, 393225674878151704,6423761195925513669, 104014146020398166139,1668870762057827073994] |