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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 4 |
| 4 | 26 |
| 5 | 230 |
| 6 | 2509 |
| 7 | 32422 |
| 8 | 484180 |
| 9 | 8203519 |
| 10 | 155460169 |
| 11 | 3257843351 |
| 12 | 74802301553 |
| 13 | 1867393802229 |
| 14 | 50358879172771 |
| 15 | 1458899632505052 |
| 16 | 45185432509804438 |
| 17 | 1489952528266230695 |
| 18 | 52112346134820625126 |
| 19 | 1926974225717684659004 |
| 20 | 75110765705496454871866 |
[1,4,26,230,2509,32422,484180,8203519,155460169, 3257843351,74802301553,1867393802229, 50358879172771,1458899632505052,45185432509804438, 1489952528266230695,52112346134820625126, 1926974225717684659004,75110765705496454871866] |