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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 87 |
| 3 | 820 |
| 4 | 6396 |
| 5 | 47452 |
| 6 | 316516 |
| 7 | 2017028 |
| 8 | 12376570 |
| 9 | 73672888 |
| 10 | 428568648 |
| 11 | 2445310419 |
| 12 | 13733337644 |
| 13 | 76104228971 |
| 14 | 416938845972 |
| 15 | 2261749445562 |
| 16 | 12163774256441 |
| 17 | 64922115452637 |
| 18 | 344182830696292 |
| 19 | 1813720428133600 |
[3,87,820,6396,47452,316516,2017028,12376570, 73672888,428568648,2445310419,13733337644, 76104228971,416938845972,2261749445562, 12163774256441,64922115452637,344182830696292, 1813720428133600] |