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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 7 |
| 3 | 68 |
| 4 | 763 |
| 5 | 9276 |
| 6 | 118656 |
| 7 | 1572024 |
| 8 | 21368155 |
| 9 | 296187164 |
| 10 | 4169180104 |
| 11 | 59420124472 |
| 12 | 855590919392 |
| 13 | 12425933510200 |
| 14 | 181787367119112 |
| 15 | 2676258927443328 |
| 16 | 39615617922076635 |
| 17 | 589234154312057436 |
| 18 | 8801406013366190952 |
| 19 | 131964659304934491576 |
| 20 | 1985338775295068132520 |
[1,1,7,68,763,9276,118656,1572024,21368155, 296187164,4169180104,59420124472,855590919392, 12425933510200,181787367119112,2676258927443328, 39615617922076635,589234154312057436, 8801406013366190952,131964659304934491576, 1985338775295068132520] |