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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 21 |
| 4 | 231 |
| 5 | 3333 |
| 6 | 58167 |
| 7 | 1175877 |
| 8 | 26827623 |
| 9 | 679078677 |
| 10 | 18844334727 |
| 11 | 568229240901 |
| 12 | 18491559492999 |
| 13 | 645850960844469 |
| 14 | 24099045218945031 |
| 15 | 956889503377128261 |
| 16 | 40291822946545245927 |
| 17 | 1793614919867776690389 |
| 18 | 84177429562216608349959 |
| 19 | 4154548653801498090246597 |
| 20 | 215137302566817565660007367 |
| 21 | 11664210072689092804458508533 |
[1,1,3,21,231,3333,58167,1175877,26827623, 679078677,18844334727,568229240901,18491559492999, 645850960844469,24099045218945031, 956889503377128261,40291822946545245927, 1793614919867776690389,84177429562216608349959, 4154548653801498090246597, 215137302566817565660007367, 11664210072689092804458508533] |