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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 20 |
| 4 | 253 |
| 5 | 3122 |
| 6 | 46651 |
| 7 | 823540 |
| 8 | 16777155 |
| 9 | 387420478 |
| 10 | 9999999939 |
| 11 | 285311670528 |
| 12 | 8916100448227 |
| 13 | 302875106592216 |
| 14 | 11112006825558003 |
| 15 | 437893890380859368 |
| 16 | 18446744073709551537 |
| 17 | 827240261886336764070 |
| 18 | 39346408075296537575383 |
[1,20,253,3122,46651,823540,16777155,387420478, 9999999939,285311670528,8916100448227, 302875106592216,11112006825558003, 437893890380859368,18446744073709551537, 827240261886336764070,39346408075296537575383] |