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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 25 |
| 4 | 337 |
| 5 | 4321 |
| 6 | 46681 |
| 7 | 437305 |
| 8 | 3721537 |
| 9 | 29740561 |
| 10 | 228000361 |
| 11 | 1699890985 |
| 12 | 12435686737 |
| 13 | 89792976001 |
| 14 | 642488104441 |
| 15 | 4567920215065 |
| 16 | 32331017955937 |
| 17 | 228106608326641 |
| 18 | 1605738151030921 |
| 19 | 11285298643841545 |
| 20 | 79223419486529137 |
[0,1,1,25,337,4321,46681,437305,3721537,29740561, 228000361,1699890985,12435686737,89792976001, 642488104441,4567920215065,32331017955937, 228106608326641,1605738151030921, 11285298643841545,79223419486529137] |