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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 10 |
| 4 | 69 |
| 5 | 616 |
| 6 | 6740 |
| 7 | 87291 |
| 8 | 1305710 |
| 9 | 22149226 |
| 10 | 420113979 |
| 11 | 8810083360 |
| 12 | 202397302184 |
| 13 | 5054993327385 |
| 14 | 136370982998354 |
| 15 | 3951907646699026 |
| 16 | 122432049983991285 |
| 17 | 4038019273764782056 |
| 18 | 141261207847788852620 |
| 19 | 5224370049771189478371 |
| 20 | 203670050053447478737214 |
[1,2,10,69,616,6740,87291,1305710,22149226, 420113979,8810083360,202397302184,5054993327385, 136370982998354,3951907646699026, 122432049983991285,4038019273764782056, 141261207847788852620,5224370049771189478371, 203670050053447478737214] |