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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 9 |
| 4 | 72 |
| 5 | 865 |
| 6 | 13803 |
| 7 | 271789 |
| 8 | 6318840 |
| 9 | 168569145 |
| 10 | 5058300495 |
| 11 | 168251893645 |
| 12 | 6134532696534 |
| 13 | 243013370253329 |
| 14 | 10384740636942483 |
| 15 | 475886186077784085 |
| 16 | 23269228564681306208 |
| 17 | 1208855249378669543785 |
| 18 | 66476561813824749886071 |
| 19 | 3857014388643231030003397 |
[1,2,9,72,865,13803,271789,6318840,168569145, 5058300495,168251893645,6134532696534, 243013370253329,10384740636942483, 475886186077784085,23269228564681306208, 1208855249378669543785,66476561813824749886071, 3857014388643231030003397] |