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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 9 |
| 3 | 67 |
| 4 | 681 |
| 5 | 8556 |
| 6 | 126253 |
| 7 | 2124340 |
| 8 | 39991633 |
| 9 | 831271006 |
| 10 | 18893178381 |
| 11 | 465972248083 |
| 12 | 12394713108433 |
| 13 | 353750057246236 |
| 14 | 10784915257548041 |
| 15 | 349874160411051511 |
| 16 | 12036066260440602401 |
| 17 | 437714593034154481686 |
| 18 | 16780944423208533034861 |
| 19 | 676482338975579658794689 |
[1,2,9,67,681,8556,126253,2124340,39991633, 831271006,18893178381,465972248083,12394713108433, 353750057246236,10784915257548041, 349874160411051511,12036066260440602401, 437714593034154481686,16780944423208533034861, 676482338975579658794689] |