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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 28 |
| 4 | 361 |
| 5 | 7061 |
| 6 | 184327 |
| 7 | 5941855 |
| 8 | 226973560 |
| 9 | 10011116097 |
| 10 | 500553647373 |
| 11 | 27975194135702 |
| 12 | 1728193768303770 |
| 13 | 116934429186262096 |
| 14 | 8600448307248025405 |
| 15 | 683181845460624644202 |
| 16 | 58290243136791332908001 |
| 17 | 5316517137637684870655592 |
| 18 | 516199318599186277653647746 |
[1,4,28,361,7061,184327,5941855,226973560, 10011116097,500553647373,27975194135702, 1728193768303770,116934429186262096, 8600448307248025405,683181845460624644202, 58290243136791332908001,5316517137637684870655592, 516199318599186277653647746] |