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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 34 |
| 3 | 368 |
| 4 | 4685 |
| 5 | 66416 |
| 6 | 1013268 |
| 7 | 16279788 |
| 8 | 271594611 |
| 9 | 4660794200 |
| 10 | 81747301898 |
| 11 | 1458812278424 |
| 12 | 26400987754054 |
| 13 | 483374731032868 |
| 14 | 8936983620559660 |
| 15 | 166617056922535080 |
| 16 | 3128790129161470470 |
| 17 | 59124052722375912960 |
| 18 | 1123458655726125274620 |
| 19 | 21452847767668402271220 |
[4,34,368,4685,66416,1013268,16279788,271594611, 4660794200,81747301898,1458812278424, 26400987754054,483374731032868,8936983620559660, 166617056922535080,3128790129161470470, 59124052722375912960,1123458655726125274620, 21452847767668402271220] |