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A221581 as a simple table
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 13 |
| 2 | 195 |
| 3 | 2730 |
| 4 | 38402 |
| 5 | 537615 |
| 6 | 7529340 |
| 7 | 105410565 |
| 8 | 1475786130 |
| 9 | 20661005638 |
| 10 | 289254613830 |
| 11 | 4049564590890 |
| 12 | 56693911799265 |
| 13 | 793714765148760 |
| 14 | 11112006817455180 |
| 15 | 155568095444334495 |
| 16 | 2177953337695895942 |
| 17 | 30491346727741970070 |
| 18 | 426878854209048054450 |
[1,13,195,2730,38402,537615,7529340,105410565, 1475786130,20661005638,289254613830,4049564590890, 56693911799265,793714765148760,11112006817455180, 155568095444334495,2177953337695895942, 30491346727741970070,426878854209048054450] |