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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 26 |
| 5 | 241 |
| 6 | 2947 |
| 7 | 45248 |
| 8 | 843732 |
| 9 | 18661671 |
| 10 | 481146211 |
| 11 | 14268787628 |
| 12 | 481575324194 |
| 13 | 18335512686481 |
| 14 | 781646971249603 |
| 15 | 37063676993936908 |
| 16 | 1943284729431092340 |
| 17 | 112059055358657319023 |
| 18 | 7072342296849963327347 |
| 19 | 486361147949618853157892 |
[0,1,1,4,26,241,2947,45248,843732,18661671, 481146211,14268787628,481575324194,18335512686481, 781646971249603,37063676993936908, 1943284729431092340,112059055358657319023, 7072342296849963327347,486361147949618853157892] |