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| n | a(n) |
|---|---|
| 0 | 4 |
| 1 | 22 |
| 2 | 210 |
| 3 | 2974 |
| 4 | 56130 |
| 5 | 1324222 |
| 6 | 37489410 |
| 7 | 1238235454 |
| 8 | 46740118530 |
| 9 | 1984855550782 |
| 10 | 93653819396610 |
| 11 | 4860878501987134 |
| 12 | 275227990564092930 |
| 13 | 16882335978752910142 |
| 14 | 1115211301788480951810 |
| 15 | 78930528072274523870014 |
[4,22,210,2974,56130,1324222,37489410,1238235454, 46740118530,1984855550782,93653819396610, 4860878501987134,275227990564092930, 16882335978752910142,1115211301788480951810, 78930528072274523870014] |