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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 5 |
| 3 | 23 |
| 4 | 156 |
| 5 | 1409 |
| 6 | 15908 |
| 7 | 215529 |
| 8 | 3406770 |
| 9 | 61542033 |
| 10 | 1250700672 |
| 11 | 28241802929 |
| 12 | 701494286870 |
| 13 | 19008349975497 |
| 14 | 557990502346020 |
| 15 | 17639808964667241 |
| 16 | 597481099591875594 |
| 17 | 21586547569205365409 |
| 18 | 828650020968205107752 |
| 19 | 33680822283049282596225 |
[2,5,23,156,1409,15908,215529,3406770,61542033, 1250700672,28241802929,701494286870, 19008349975497,557990502346020,17639808964667241, 597481099591875594,21586547569205365409, 828650020968205107752,33680822283049282596225] |