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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 4 |
| 4 | 17 |
| 5 | 76 |
| 6 | 357 |
| 7 | 1737 |
| 8 | 8997 |
| 9 | 49420 |
| 10 | 289253 |
| 11 | 1793221 |
| 12 | 11727861 |
| 13 | 80576965 |
| 14 | 579781009 |
| 15 | 4356513727 |
| 16 | 34118896917 |
| 17 | 277963716808 |
| 18 | 2351740613433 |
| 19 | 20630800971825 |
| 20 | 187374815249205 |
| 21 | 1759353644746663 |
| 22 | 17055176943817785 |
| 23 | 170477858336708555 |
| 24 | 1754992340756441973 |
[1,4,17,76,357,1737,8997,49420,289253,1793221, 11727861,80576965,579781009,4356513727, 34118896917,277963716808,2351740613433, 20630800971825,187374815249205,1759353644746663, 17055176943817785,170477858336708555, 1754992340756441973] |