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| n | a(n) |
|---|---|
| 1 | 21 |
| 2 | 154 |
| 3 | 823 |
| 4 | 5463 |
| 5 | 33853 |
| 6 | 223869 |
| 7 | 1454613 |
| 8 | 9620565 |
| 9 | 63336647 |
| 10 | 419113710 |
| 11 | 2770472419 |
| 12 | 18336620495 |
| 13 | 121358670826 |
| 14 | 803332031961 |
| 15 | 5318434541385 |
| 16 | 35208666237989 |
| 17 | 233111781026276 |
| 18 | 1543314708909090 |
| 19 | 10218090869079319 |
[21,154,823,5463,33853,223869,1454613,9620565, 63336647,419113710,2770472419,18336620495, 121358670826,803332031961,5318434541385, 35208666237989,233111781026276,1543314708909090, 10218090869079319] |